I dont think Id refer to it as proof, since only the gay catholic priests themselves know, and have incentive to keep it quiet.
However I did post links to information on a thread last week.
Here is a quote, which you could google if you want to learn more.
One of their trusted sources told them, for example, that the Vaticans personnel is about 50% homosexual. Also discussing the recent article written by Andrew Sullivan The Gay Church the journalists of Church Militant agree with the substantive research that, among parish priests, there can be found to be as many as 40-60% who are homosexual.
You can assume 1/3 to 1/2 of the priests at your parish are gay. Ask, if you care - and I assume any Christian would.
Rome has become the gayest religion on earth, by numbers.
A book written by a gay sociologist? Really?