Why is there a lack of male supermodels?

I am not trying to be sexist or anything but if many girls are becoming supermodels, why aren't any guys attaining that status? Is it because female modeling is more rewarding, is it because girls are stronger in that area, or is it because of the society? So far I only know of Will Chalker almost reaching that status but not quite since he still isn't the next male Gisele or Tyra or Doutzen for that matter.