Well, I think most people are only in a couple of the fandoms on this list - I think of myself as someone who very much *does* follow the fandom mainstream, and there's only five of the top fifteen that I'm willing to read at all, and only two where I'd say I'm currently in the fandom (and only one where I ship it.) Fandoms get on this list by being a lot of people's one or two, not everybody's hundred!

Mulder/Scully absolutely surprised me though, I hope there is still good stuff being written for it! I got into it just as the show was ending and still have a fondness, though I never really shipped MSR.