The 95/5 split would represent roughly the demographics of RPGs circa 1985. I'd be both surprised if the modern demographics are the same, or that they had shifted greatly from that. My guess is that real percentage of female RPG gamers is round 10-15%.
What is probably the cause of the under representation is not activity but level of interest. Nerddom has a certain obsessiveness to it that I think skews male.
In my experience the largest percentage of female gamers always tends toward significant others and family members of a male gamer.
I've got a daughter that has the personality for it and interest in gaming, but I'm fairly sure that she's not going to find enough girls of like interest to have an RPG group and ultimately she's likely to have more friends that are boys than girls. Already she's socially suffering because in her peer group there is a mass falling away from the casual live action RP (make believe) she's preferred as play in favor of more traditional girl interests, and I'm not silly enough to believe that no biology is at play in that. For one thing, it amounts to suggesting that things that men are traditionally interested in are more worthy of approval and important.
I was watching a documentary about a young girl's attempt to sail around the world solo, and it became clear to me very early on that it was never going to happen. Because while the girl did enjoy sailing, it was clear very early on that even more than she enjoyed sailing, she enjoyed having an activity that she could share in with her father and receive his full interest and approval. Without her family members with her, particularly her father, it simply wasn't something she enjoyed enough on its own to make it worth the difficulties there of.
And that's my impression of 3/4's of the women playing RPGs. They enjoy it. But if it wasn't for the fact that this was something that brought them closer to their male friends and loved ones, most wouldn't do it. So it's possible that even if the split is now 80/20 or something, that 3/4's of the women playing aren't involved enough to bother coming to someplace like EnWorld.
Personally, I prefer a mixed table, but I admit its now been a long time since I've had one. My own personal preferences of play are highly eclectic. I feel cheated when a game is only dramatic, only tactical, only puzzle-solving, or lacks exploration both of theme, character and space. When a group skews male only, it tends to skew toward a single style of play and the game for me tends to feel less cooperative, as the players tend to view the game largely as a competition between themselves and me, rather than something we are creating together. Moreover, all male groups in my experience don't learn to play. They mostly unlearn to play, so that over time the quality of play tends to deteriorate and become less playful. I'm certainly seeing this in my own group. Intra-party play is increasingly over time taking a confrontational, combative, defensive approach that is highly focused on essentially bullying the other PC/player to achieve some end, rather than any sort of character based or emotional exploration. And that's largely because the role-play itself is not taken to be the point by the player, but rather solely as a means to an end ("winning"). Ironically, this approach means that the player is less likely to achieve meta-goals than if they took more expressive, exploratory and less confrontational approaches.
I don't know how many times I get approached by supposedly mature experienced male RPers concerning some metagoal that they have and how they should go about accomplishing it, when my advice to them basically amounts to, "If this is such an important goal for you, why haven't you in any way directed play in character toward these goals. You've never explored the environment for this purpose. Never searched, questioned, or interacted with an NPC in a way that made clear that you were looking for this thing. If you want to find this sort of thing, you are going to have to actively steer toward that goal. I'm not simply going to put the group on rails and plop you down where you want to be." I've never had to say that to a female gamer.
Stereotypes? Yeah, probably. But I'm not sure they are unfair stereotypes. They are limited only in the sense you always no more by finding out who an individual is than you know by simply knowing which aggregate group they belong to. There are always exceptions to the mode and the mean, and mainly you get in trouble when you start thinking the mode or the mean is all there is or all that should be.
