How many tilesets there are with sizes in each range of hundred tiles. We can see the most common size for a tileset is between 900 and 999 tiles, and it's hugely uncommon to have more than 1099 tiles, which is understandable because the maximum size for a 1.23-compatible tileset is 1020 tiles. Alternate palettes are counted separately, because they are separate .j2t files: for example there are fully seventeen different Improved Medivo palettes, all of which are 960 tiles.

September 2017 is an arbitrary cutoff date in that it's when I got stijn's J2O dump, but it's also pretty convenient in that MLLE's "Save Tileset Images" tool was added just a few months later, and that would confuse the higher number data.