Apparently, quite a number of users have been deleted in the last month or so. I've noticed it because, as I haven't been very active lately, my rep score has been declining due to their removed votes.

I saw that 155 users have been deleted in the whole year, so unless they'd been very active in voting, the 5 I noticed seem quite a lot.

Is there some sort of end-of-the-year clean up taking place, an exodus, or is it just a fluke?