As at the begin of every new quarter since a couple of years, I’ve updated the Contributor Statistics on our wiki.
Naturally the most noticeable thing is the large jump in new users and active users starting in April 2016, which is naturally mainly due to new incoming edits from maps.me users. This is, on first principles, naturally not a bad thing, and annoyances due to bad edits aside, exposing more people to OSM is good.
What I have however noted in discussion is that the impact of the growth of the raw number of contributors is massively overestimated. For example the number of edits (not changesets) per month is essentially unchanged: