Active admins as an example of entrances and exits
Fragment of a discussion from Talk:Editor Trends Study
I've been fairly active in the RFA process on EN Wiki and nominated half a dozen of the last hundred new admins.
I haven't done a scientific sample, but most of the people I've nominated I first approached by Email, and I've approached a much larger number who I thought would make good admins. Most of the people I've approached have turned me down, and most of them because they don't fancy RFA.