In Penn & Teller's Bullshit, Season 7, there is an episode about the Vatican. I just watched it via this post on the blog, Arizona Atheist.
In it, around the 8m:10s mark, a statement is made that around 20-50% of Catholic priests may be homosexual. I'm transcribing the episode here for the pertinent quote. It opens with Keith Wood, the executive director of The National Secular Society, making a comment about the Catholic Church's opposition of homosexuality:
Keith Wood: And the almost ultimate irony is that I do not know of an organization anywhere that has such a high proportion of gay people in its employ.
Penn Jillette: Well, the Bullshit staff, but he doesn't know that. According to some studies, somewhere between twenty (20) and fifty (50) percent of all priests may be gay.
What studies/data support this estimate, and is it accurate?