How often do pretty girls get asked out?

[J]

I'm just wondering, because, just looking at some girls' Facebook pages, it seems like they go for years without a boyfriend. Even on their walls, it's mostly their girlfriends asking to hangout. I seldom see guys hitting on them (apart from the odd stalker, who she obviously isn't going to go out with)

Are they just not getting asked out much? Or are they super picky? Or are they being discreet and having lots of flings?

Just curious. Because if nobody else is asking them out, then I will! LOL