This is probably active ones too, so the ones that don't comment (like me) don't count.. except this time. I would say it would be around same size as the active ones, but I have no data to prove that.
Though I think there are probably people who only lurk (not even a vote) like me on reddit, but that's probably less people, since unlike reddit, where it's very searchable (through search engines, I mean) so you have to access it for some use case.