(NSFW) How common is beastiality?

Inspired by http://www.fluther.com/disc/76876/nsfw-what-is-something-that-you-refuse-to-try-during-sex/.

I noticed a fair number of people mentioned they refuse to try this – does anyone have a friend or acquaintance that has? Just how common is this practice? Personally I can’t wrap my head around what could possibly be attractive about it, but I suspect it’s a lot more common than were led to believe. Thoughts?