Current breakdown at the time of this post sorted by the number of monthly active users:

1. lemmy.world: 101,013 total users / 27,472 active users
2. lemmy.ml: 41,972 total users / 4,905 active users
3. beehaw.org: 12,270 total users / 4,178 active users
4. sh.itjust.works: 17,509 total users / 3,381 active users
5. feddit.de: 8,675 total users / 2,935 active users
6. lemm.ee: 10,348 total users / 2,751 active users
7. lemmynsfw.com: 22,967 total users / 2,310 active users
8. lemmy.fmhy.ml: 8,777 total users / 1,704 active users
9. lemmy.ca: 5,072 total users / 1,656 active users
10. programming.dev: 5,058 total users / 1,242 active users

Source: https://the-federation.info/platform/73