Looking back at me gaming groups, I can note the following:
High School - 2 GMs, I was 1 of them
Summer Poconos Group - I was the only GM
College D&D Club - I was the only DM in a group of 12+
College / Post College Home Group - 2 GMs, I was 1
Roll20 / G+ Hangouts - of the 7 mostly regular members, everyone has run at least a session
What is it with the latest group? I think the common factor is everyone is a creative type - artists, writers or both.
We also all enjoy filling the roll of the GM or the player.
While GMing is a skill, it is also a calling. Not everyone has the desire to be a GM and that's okay. Really. At a gaming table of 3 to 8 gamers, only one can fill the roll of a GM at a time.
I'd also expect that in most groups, especially those that are composed of mostly newer players, the GM roll is filled by by one of the more experienced gamers at the table.
So, I'm going to hazard a guess that 2 out of 3 RPG gamers see themselves as primarily "players."
I do expect the poll I'm going to run will prove those numbers wrong, but I also expect that gamers active in blogs and social media are more on the GM side of the fence.
More thoughts on this later.