At the beginning of March 2021 there were 324234 user profiles in the ranking list on Codeforces (my code on GitHub). About a quarter of them (81918 users) took part only in 1 contest.

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A little bit more (86008 users) took part in 2,3 or 4 contests. And about a quarter of all users (75292) took part in number of contests from 5 to 12. The last quarter I've divided into two, and so on, and so on. 81016 users took part in 13 contests or more, 20235 users in 43+, 4957 users in 84+, 1207 users in 134+ contests.