In a different thread on piano world a poster did an estimate of the number of composers on the IMSLP site. They calculated it was around 50,000(Or maybe 30,000 since I just noticed Sidokar's post On this thread)
so I think the first figure for total number of classical composers mentioned in the OP is probably way too small.
Scott Joplin is the list, but way towards the bottom. If you were compiling a list of composers whose music got played, period, and not just in recitals, he would probably be much further up the list. Then there's the question of whether ragtime belongs in classical repertoire or elsewhere.
Sam Another thing to bear in mind with the Carnegie Hall database is that it goes back to the 1890s.
Very interesting. It would be interesting to see a plot of what got played changed over the years.
Pallas
I’m interested in this. Do you have any ideas where to look for an answer? I started studying classical piano so I have the skill to play film scores, advanced versions of American standards, and ragtime among other things. I understand that “classical” is both an umbrella term and a specific genre, and much film score music is often called “neoclassical,” but in my admittedly uninformed way I’ve been pretty focused on transferable skills, and if it’s complexity that assigns genre, lots of non-classical is plenty complex, sophisticated stuff just looking at scores. If this should be a separate topic, please say, otherwise, I might post a page from a book I just got of ragtime written during the 1970s revival to see what you advanced pianists might say about its flavor (is it classical, why or why not?)
At the University I attended (and probably all schools in the US), ragtime was accepted for required recitals as a modern piece. At least Scott Joplin was. This was at the undergraduate level. Might be too easy for graduate level recitals. And this was a typical regional US university, not a conservatory or a prestigious school.
Pallas
"Modern" is an umbrella term that covers a vast variety of musical styles. I don't really agree on putting all 20th century music in one bucket. Each style has specific challenges.
Ragtime is harmonically very "classical" but the main difficulty is the rhythm, especially the typical ragged syncopation.
Film music is relatively straightforward (once you reach a certain level) because it often has a more transparent texture and lots of repeating patterns, much like the classical era but with more modern harmonies.
Pop is harmonically simple (although unlike rag it uses modern harmonies) but has a lot of rhythmic difficulties. There is rarely a pop tune that doesn't syncopate. Almost all pop is on the off beat (2 and 4) and that is usually emphasized strongly in the LH while the melody is syncopated.
Jazz is hard. Harmonically, melodically, rhythmically. And there's the whole improvisation thing too. Maybe I'll figure it out one day... 
One other factor (if it hasn't been mentioned already) is that a number of the composers on that "top 100" either wrote very little for solo piano (Wagner), or lived at a time before the piano as we know it today existed.
Is this chart really reflective of solo keyboard music of all types?
I love the way this discussion has shifted to what counts as classical...
Re being born in the US, how about Billy Joel? And no, I don't mean his pop music, I mean his solo, classical piano music.
I think this is it:
OTOH, there's this, I Gironi, by Einaudi, which I always think of as having a very "popular music" feel, not pop music, but modern contemporary solo piano that I would call more "popular" than "classical." I think it's the chord progressions for me. Give a listen and tell me what you think:
I have seen ragtime categorized as straddling both the classical and jazz genres. As Bart said above, there is a classical feel to the music, but the syncopations seem to many people to be foreign or exotic to classical music. Even amongst ragtime, where a piece fits can vary considerably. Compare Maple Leaf Rag with Solace (both by Joplin). Where would Graceful Ghost (Bolcom) fit? BTW, Graceful Ghost is one of my all-time favorite pieces of music. But it is way too difficult for me to play. I started to learn Solace (another beautiful piece) several years ago, put it aside, and came back to it last fall and got much further with it, but it's still not 100%. I admit to being somewhat ragtime-rhythm challenged. 
In fact imslp doesnot have all the composers of classical music. It has only only those for which we have works in a written form. But numerous composers either never published anything or their work was lost. So the 30000 can be considered as a minimum. Of course many of them are minor composers. And the question of what can be considered as classical is also to be factored.
Pallas Bolcom won the pulitzer prize for his music and was a composition professor at the University of Washington. But even better, Marc Andre Hamelin recorded all of his rags. So they are a part of the "classical" repertoire. But so is his atonal music, like the etudes. Here is his non-tonal rag - all the elements of ragtime, but not tonal:
I counted that I've played at least one keyboard work by 13 "classical" composers not on the list.
Interesting that Poulenc and Milhaud are the only members of Les Six who are represented on the list.
Ithaca My brain automatically categorizes this as (popular) modern contemporary and definitely not classical, but I can't tell you why. (I could theorize, but really I'd be guessing.)
I’m glad you hear it that way too! I do think it’s the chord progressions, but I could be wrong. It’s been a while since I’ve played it, maybe I should it back in my practice rotation and see if I think of it the same way.
On a different note - wow, I had no idea that Billy Joel was capable of this level of composition. When I think of him, I just think of that spooky drugged-out photo of him on the Piano Man cassette. Thanks for posting the Fantasies & Delusions link.
You’re welcome! When I was a kid (in junior high maybe?) I was really into Billy Joel (his rock/pop stuff). I started piano as an adult, in 1999. The score and recording of Fantasies and Delusions was released in 2001, my mother got it for me as a present. There was (and still is, I imagine) no way I could play these pieces, too advanced for me. But I think the pieces are wonderful. Somehow, to me, the pieces sound both contemporary and very traditionally “classical” at the same time. Whatever that means. 
Perhaps the reason why Poulenc and Milhaud are on the list, as opposed to Honegger, Auric, Tailleferre, and Durey has to do with the amount of piano music written/performed/recorded.
There are quite a few well-known pieces by Poulenc that have been recorded many times, same for Milhaud (especially the early pieces he wrote while living in Brazil, and some of the works he wrote during the 1920s).
Regarding the pieces by Billy Joel, I note that they were arranged by someone else. It's not clear what that means in terms of the more "classical" & "pianistic" elements of the compositions.
pseudonym58 Regarding the pieces by Billy Joel, I note that they were arranged by someone else. It's not clear what that means in terms of the more "classical" & "pianistic" elements of the compositions.
Good point. I hadn't really noticed that. They are arranged by the pianist who performed them on the recording. To me the question is, how much "arranging" was there, and how "classical" were Billy Joel's original (unarranged) compositions.
I'll have to look at my sheet music for this when I get home and see if it says anything beyond the "arranged by" part.
for what it's worth, here's the Wiki entry. Not much info...
https://en.wikipedia.org/wiki/Fantasies_%26_Delusions
Scott Joplin is the on list, but way towards the bottom. If you were compiling a list of composers whose music got played, period, and not just in recitals, he would probably be much further up the list.
If you include players of all levels, Bach's Anna Magdalena notebook and Schumann's Album for the Young may be the most played pieces.
I think players with the ability to play Joplin rags well have studied the music of major classical piano composers and play a diverse repertoire. There are some pianists who choose to specialize in ragtime, but I think there are far fewer of them than pianists who play traditional classical repertoire.
I do find Joplin's music to be much closer to classical piano than to jazz harmonically, as noted upthread by BartK. Joplin was influential on jazz musicians, though more through usage of rhythms than through harmony or form.
In the mid-19th century, I think Handel and Mozart would have been at the top of the list (which of course would have been shorter than 100), but Scarlatti would have been omitted. My understanding is that Scarlatti's music was brought to the attention of classical pianists by virtue of Horowitz having included it in his repertoire.
Sadly, Handel's music seems to have fallen off of the recital programs of professional pianists.
Tbh isn't this just another instance of the Pareto principle? There's nothing that special here.
The Pareto Principle would have about 20% of composers represented on about 80% of recital programs. The above list is much more skewed than that, to the extent of more being an exception to, rather than example of the Pareto Principle.
Just to give people something else to talk about, here are the top 100 pieces performed at Carnegie Hall, as extracted by me (probably with some errors) from the database over the time period from the first recital to 2018 (about 120 years).
Rank Work Total Performances Plot List
1 Chopin,Frederic,Ballade No. 1 in G Minor, Op. 23 280 Plot List
2 Beethoven,Ludwig van,Piano Sonata No. 23 in F Minor, Op. 57, "Appassionata" 260 Plot List
3 Chopin,Frederic,Piano Sonata in B Minor, Op. 58 249 Plot List
4 Chopin,Frederic,Ballade No. 4 in F Minor, Op. 52 235 Plot List
5 Chopin,Frederic,Piano Sonata in B-flat Minor, Op. 35 231 Plot List
6 Liszt,Franz,Piano Sonata in B Minor, S. 178 (R. 21) 228 Plot List
7 Chopin,Frederic,Polonaise in A-flat Major, Op. 53 222 Plot List
8 Chopin,Frederic,Ballade No. 3 in A-flat Major, Op. 47 216 Plot List
9 Chopin,Frederic,Barcarolle in F-sharp Major, Op. 60 213 Plot List
10 Chopin,Frederic,Scherzo No. 2 in B-flat Minor, Op. 31 202 Plot List
11 Chopin,Frederic,Scherzo No. 3 in C-sharp Minor, Op. 39 201 Plot List
12 Chopin,Frederic,Fantasie in F Minor, Op. 49 197 Plot List
13 Schumann,Robert,Carnaval, Op. 9 187 Plot List
14 Schumann,Robert,Fantasy in C Major, Op. 17 178 Plot List
15 Beethoven,Ludwig van,Piano Sonata No. 21 in C Major, Op. 53, "Waldstein" 177 Plot List
16 Beethoven,Ludwig van,Piano Sonata No. 32 in C Minor, Op. 111 174 Plot List
17 Schumann,Robert,Études symphoniques, Op. 13 163 Plot List
18 Beethoven,Ludwig van,Piano Sonata No. 31 in A-flat Major, Op. 110 159 Plot List
19 Beethoven,Ludwig van,Piano Sonata No. 30 in E Major, Op. 109 157 Plot List
20 Chopin,Frederic,Andante spianato et Grande polonaise brillante, Op. 22 151 Plot List
21 Chopin,Frederic,Scherzo No. 1 in B Minor, Op. 20 149 Plot List
22 Debussy,Claude,L'isle joyeuse 146 Plot List
23 Chopin,Frederic,Nocturne in D-flat Major, Op. 27, No. 2 145 Plot List
24 Chopin,Frederic,Berceuse in D-flat Major, Op. 57 145 Plot List
25 Beethoven,Ludwig van,Piano Sonata No. 14 in C-sharp Minor, Op. 27, No. 2, "Moonlight" 145 Plot List
26 Bach,Johann Sebastian,Chromatic Fantasia and Fugue in D Minor, BWV 903 126 Plot List
27 Mussorgsky,Modest,Pictures at an Exhibition 123 Plot List
28 Liszt,Franz,Mephisto Waltz No. 1, S. 514, "Der Tanz in der Dorfschenke" 123 Plot List
29 Chopin,Frederic,Ballade No. 2 in F Major, Op. 38 119 Plot List
30 Beethoven,Ludwig van,Piano Sonata No. 26 in E-flat Major, Op. 81a, "Les adieux" 111 Plot List
31 Debussy,Claude,Préludes, Book II: Feux d'artifice 110 Plot List
32 Brahms,Johannes,Variations and Fugue on a Theme by Handel, Op. 24 109 Plot List
33 Brahms,Johannes,Piano Sonata No. 3 in F Minor, Op. 5 109 Plot List
34 Schumann,Robert,Kreisleriana, Op. 16 108 Plot List
35 Bach,Johann Sebastian,Chaconne from Violin Partita No. 2 in D Minor, BWV 1004 105 Plot List
36 Beethoven,Ludwig van,Piano Sonata No. 17 in D Minor, Op. 31, No. 2, "The Tempest" 104 Plot List
37 Chopin,Frederic,Fantaisie-Impromptu in C-sharp Minor, Op. 66 101 Plot List
38 Chopin,Frederic,Étude in C Minor, Op. 10, No. 12 99 Plot List
39 Ravel,Maurice,Gaspard de la nuit 95 Plot List
40 Chopin,Frederic,Étude in E Major, Op. 10, No. 3 95 Plot List
41 Chopin,Frederic,Waltz in C-sharp Minor, Op. 64, No. 2 95 Plot List
42 Chopin,Frederic,Nocturne in C Minor, Op. 48, No. 1 93 Plot List
43 Prokofiev,Sergey,Piano Sonata No. 7 in B-flat Major, Op. 83 92 Plot List
44 Chopin,Frederic,Étude in C-sharp Minor, Op. 10, No. 4 91 Plot List
45 Chopin,Frederic,Polonaise in F-sharp Minor, Op. 44 91 Plot List
46 Beethoven,Ludwig van,Piano Sonata No. 8 in C Minor, Op. 13, "Pathétique" 91 Plot List
47 Beethoven,Ludwig van,Piano Sonata No. 18 in E-flat Major, Op. 31, No. 3 90 Plot List
48 Liszt,Franz,Grandes études de Paganini, S. 141: Étude No. 3 in G-sharp Minor, "La campanella" 88 Plot List
49 Chopin,Frederic,Impromptu in F-sharp Major, Op. 36 86 Plot List
50 Chopin,Frederic,Polonaise-Fantaisie in A-flat Major, Op. 61 85 Plot List
51 Chopin,Frederic,Nocturne in F-sharp Major, Op. 15, No. 2 85 Plot List
52 Beethoven,Ludwig van,Thirty-Two Variations on an Original Theme in C Minor, WoO 80 85 Plot List
53 Schubert,Franz,Fantasy in C Major, D. 760, "Wandererfantasie" 84 Plot List
54 Chopin,Frederic,Étude in A-flat Major, Op. 25, No. 1 83 Plot List
55 Ravel,Maurice,Sonatine in F-sharp Minor 81 Plot List
56 Brahms,Johannes,Variations on a Theme by Paganini, Op. 35 81 Plot List
57 Liszt,Franz,Années de pèlerinage, 2e année, Italie, S. 161: 5. Sonetto del Petrarca No. 104 80 Plot List
58 Chopin,Frederic,Scherzo No. 4 in E Major, Op. 54 80 Plot List
59 Ravel,Maurice,Jeux d'eau 79 Plot List
60 Schumann,Robert,Arabeske, Op. 18 78 Plot List
61 Debussy,Claude,Préludes, Book I: La cathédrale engloutie 78 Plot List
62 Liszt,Franz,Hungarian Rhapsody No. 12 in C-sharp Minor, S. 244, No. 12 (R. 106) 77 Plot List
63 Franck,César,Prélude, choral et fugue 77 Plot List
64 Beethoven,Ludwig van,Piano Sonata No. 7 in D Major, Op. 10, No. 3 77 Plot List
65 Beethoven,Ludwig van,Piano Sonata No. 28 in A Major, Op. 101 77 Plot List
66 Chopin,Frederic,Étude in C-sharp Minor, Op. 25, No. 7 76 Plot List
67 Chopin,Frederic,Nocturne in C-sharp Minor, Op. 27, No. 1 75 Plot List
68 Rachmaninoff,Sergei,Prelude in G-sharp Minor, Op. 32, No. 12 74 Plot List
69 Mendelssohn,Felix,Variations sérieuses, Op. 54 74 Plot List
70 Chopin,Frederic,Impromptu in A-flat Major, Op. 29 72 Plot List
71 Schubert,Franz,Piano Sonata in B-flat Major, D. 960 71 Plot List
72 Rachmaninoff,Sergei,Piano Sonata No. 2 in B-flat Minor, Op. 36 71 Plot List
73 Debussy,Claude,Images, Set I: Reflets dans l'eau 71 Plot List
74 Chopin,Frederic,Twenty-Four Preludes, Op. 28 71 Plot List
75 Prokofiev,Sergey,Piano Sonata No. 3 in A Minor, Op. 28 70 Plot List
76 Liszt,Franz,Harmonies poétiques et religieuses, 2nd version, S. 173: 7. Funérailles (R. 14, No. 7) 70 Plot List
77 Schubert,Franz,Impromptu in G-flat Major D. 899, No. 3 69 Plot List
78 Bach,Johann Sebastian,Concerto in the Italian Style, BWV 971 67 Plot List
79 Mozart,Wolfgang Amadeus,Piano Sonata in C Major, K. 330 66 Plot List
80 Ravel,Maurice,Valses nobles et sentimentales 65 Plot List
81 Rachmaninoff,Sergei,Prelude in G Minor, Op. 23, No. 5 65 Plot List
82 Chopin,Frederic,Waltz in A-flat Major, Op. 42 65 Plot List
83 Bach,Johann Sebastian,Toccata and Fugue in D Minor, BWV 565 65 Plot List
84 Rachmaninoff,Sergei,Prelude in G Major, Op. 32, No. 5 64 Plot List
85 Debussy,Claude,Préludes, Book II: Ondine 64 Plot List
86 Chopin,Frederic,Étude in G-flat Major, Op. 10, No. 5 64 Plot List
87 Chopin,Frederic,Mazurka in A Minor, Op. 17, No. 4 64 Plot List
88 Liszt,Franz,Hungarian Rhapsody No. 6 in D-flat Major, S. 244-6 63 Plot List
89 Mozart,Wolfgang Amadeus,Rondo in A Minor, K. 511 62 Plot List
90 Liszt,Franz,Années de pèlerinage, 2e année, Italie, S. 161: 7. Après une lecture du Dante 62 Plot List
91 Chopin,Frederic,Étude in G-sharp Minor, Op. 25, No. 6 62 Plot List
92 Chopin,Frederic,Waltz in E-flat Major, Op. 18 62 Plot List
93 Beethoven,Ludwig van,Piano Sonata No. 29 in B-flat Major, Op. 106, "Hammerklavier" 62 Plot List
94 Schumann,Robert,Piano Sonata No. 2 in G Minor, Op. 22 59 Plot List
95 Liszt,Franz,Rhapsodie espagnole, S. 254 59 Plot List
96 Chopin,Frederic,Étude in G-flat Major, Op. 25, No. 9 59 Plot List
97 Chopin,Frederic,Étude in A Minor, Op. 25, No. 11, "Winter Wind" 59 Plot List
98 Schumann,Robert,Kinderszenen, Op. 15 58 Plot List
99 Mozart,Wolfgang Amadeus,Piano Sonata in A Minor, K. 310 57 Plot List
100 Beethoven,Ludwig van,Piano Sonata No. 13 in E-flat Major, Op. 27, No. 1, "Quasi una fantasia" 57 Plot List
If you want a particular composers works listed by order of performances, I can probably do that too.
Sam
