This question is an offshoot of Ben Crowell's question Have we lost the necessary critical mass of professional physicists?, and I'm asking it separately to help avoid multi-threaded comment discussions.
I'm particularly interested in a comment of dmckee:
I don't think that we (that is the mods) should be in the business of closing a lot of questions with our super-powers anymore. There are enough 3k users (81) that they should be able to carry the bulk of the load. My impression, however, is that a relatively small fraction of the eligible users apply their power with any regularity.
As I said in that thread, I think this is a specific enough question that we can find the relevant statistics to give an answer to it. I must add that I agree with dmckee's impression.
So, the specific question: Is it possible to confirm this statement from publicly available data, hopefully through the data explorer? If so, what, exactly, are the relevant statistics to ask for?
To kick off the discussion, and to answer Manishearth's comment, I think the relevant tables to look at are not the per-question close-votes, but the publicly available per-user log of the review activity.
OK, so it looks we may need to ask the dev team for these statistics. In this case, what, exactly, are the relevant statistics to ask for? I'll make a proposal shortly but please try and think of others.