I was flipping through an American bridal magazine [don't remember which] and found that statistic, which was stated in the positive: 1/3 of weddings take place in a house of worship.
I know outdoor weddings are popular on theknot, but I also know theknot, both people here in the boards, and particularly the weddings submitted on the main site, is skewed towards the less traditional and more expensive. It's a for-profit enterprise, after all, and traditional weddings are simple and therefore relatively inexpensive.
Anyway, it was interesting to read.