Charwoman Gene
Adventurer
Hmmm... maybe see what was registered for a recent con? See who played what. I think that, other than some poll or survey, would be your best bet for solid numbers.
I go to some cons where no one runs D&D because they play D&D at home and want a change. WHen someone actually puts a D&D table up they fill up massively and quick. Play at cons does not equal play overall.