The methodology for these numbers changed in Q2 2019[1], so I don't think it's safe to compare 2014 numbers to 2021. However, Q2 2019 is well before FoundryVTT exited beta, so it is safe to look at the 2019 numbers and draw conclusions about online play:

  D&D 5e: 51.87%
  Uncategorized: 14.27%
  Call of Cthulhu: 9.48%
  Pathfinder: 6.46%

[1] https://blog.roll20.net/posts/the-orr-group-industry-report-...