How many men are pedophiles?

The BBC has an article by Wesley Stephenson about that terrible question:

The Pope was recently reported to have said that about two percent of Catholic clergy are pedophiles. But how does this compare with society as a whole: is it more or less than average? As soon as you give this question a moment's thought, you realise that it's not going to be an easy one to answer. Pedophiles are not easy to identify.
"Because pedophilia is so secretive and so few people are willing to admit it, there is no meaningful way to get a reliable estimate," says Dr. James Cantor, a psychologist and sexual behavior scientist at the University of Toronto in Canada. "There's no meaningfully ethical way of taking two hundred men, hooking them up to detectors, showing them pictures of adults and children and seeing how many respond most to children."
One person who has attempted an estimate is Dr. Michael Seto, a clinical and forensic psychologist at the Royal Ottawa Healthcare group. In 2008 he wrote a book in which he put the prevalence of pedophilia in the general population at five percent.
The figure was based on surveys conducted in Germany, Norway, and Finland, in which men were asked whether they had ever had sexual thoughts or fantasies about children or engaged in sexual activity with children.
But Seto stresses that five percent was an upper estimate, and that the studies were limited in what they revealed. "What those surveys do not include are questions on the intensity of those thoughts and fantasies, whether they were repeated or not. Someone might say 'Yes' because they once had a fantasy, but our understanding of pedophilia would be that that person had sexual thoughts and fantasies about children." Now, with more data and better methodology, he has revised his figure down to about one percent of the population, though he makes clear this is still only an educated guess.
One problem is that the term "pedophile" means different things to different people.
"It's very common for regular men to be attracted to eighteen-year-olds or twenty-year-olds. It's not unusual for a typical sixteen-year-old to be attractive to many men, and the younger we go the fewer and fewer men are attracted to that age group," says Cantor.
He thinks that if we say that a pedophile is someone attracted to children aged fourteen or less, then he estimates that you could reach the two percent figure. "If we use a very strict definition and say pedophilia refers only to the attraction to pre-pubescent children, then it is probably much lower than one percent," he says.
The term is often applied to a person who sexually abuses someone below the age of sixteen, but given that in some countries, and even some US states, you can marry below the age of sixteen, this definition would clearly not be universally accepted.
There is consensus on the clinical definition. Michael Seto and his colleagues agree that a pedophile is someone who has a sexual interest in pre-pubescent children, so typically those under the ages of eleven or twelve.
But whether the prevalence using this definition is a half a percent, as James Cantor says, or one percent, as Michael Seto says, you can be assured than in any large group of people, whether they be politicians, entertainers, or Catholic clergy, you are likely to find some pedophiles.
Pedophilia is not restricted to men; some women also sexually abuse children, although research suggests this is much less common.
But back to the Pope. How would he define "pedophile"? We don't know, but there is a clue. There is one well-known study of pedophilia among Catholic clergy, carried out by the John Jay College of Criminal Justice in New York City. Its researchers went to each diocese in the US and found all the plausible accounts of abuse involving clergy who served between 1950 and 2002, and they found that just over four percent had been plausibly accused of abuse.
That included allegations of abuse of adolescents as well as pre-pubescent children.
But if you use the stricter, clinical definition of pedophilia the figure drops to between one and two percent according to Professor Philip Jenkins from the Institute of Studies of Religion at Baylor University in Waco, Texas. This corresponds, more or less, with the figure attributed to the Pope. "If he was using a different word like 'abusive clergy' then I think he would be going for a higher figure," says Jenkins.
The John Jay College study is not perfect, though. For some reason, forty percent of the allegations referred to abuse said to have been carried out in a six-year period between 1975-1980. It seems unlikely that cases of pedophilia in the clergy would have been so heavily concentrated in one period. Furthermore, even if there was a peak in the 1970s, a lot of the perpetrators are probably no longer active in the church.
All we can confidently say is that, firstly, the figures are imperfect, both for Catholic clergy and the general population. And secondly, that these imperfect figures are in the same ballpark.

Rico says we're back to Shakespeare again: Who will rid me of this troublesome priest? (But, since you asked, no, not with a gub to Rico's head...)