Well supposedly the FBI watched as over 5,200 people signed up for CP, cross-checked 3,500 names for Pentagon ties, 264 individuals were uncovered as being specifically Pentagon employees or contractors, including staffers for the Secretary of Defense, and then only 20 percent of these 264 people were completely investigated and fewer still were prosecuted. 1,700 alleged child porn customers still went unchecked.

And that's just what the MSM was willing to admit to back then: http://ireport.cnn.com/docs/DOC-1184433

Quick search shows that "approximately 23,000 military and civilian employees and about 3,000 non-defense support personnel work in the Pentagon."

So let's just give them the best benefit of the doubt we can and assume that it was only 264 staff members out of roughly 26,000. So that would be a but over 1% (1.0153846153846153% according to this site that does the math for me) of Pentagon staff definitely caught accessing CP. Although of course we can all probably safely assume it was more than that since thousands of cases were never even checked.

Dr Michael Seto, a clinical and forensic psychologist claimed in 2014 that he thinks that if we say that a paedophile is someone attracted to children aged 14 or less, then he estimates that you could reach the 2% figure, and that if we use a very strict definition and say paedophilia refers only to the attraction to pre-pubescent children [then it] is probably much lower than 1%. Dr James Cantor, a psychologist and sexual behaviour scientist claimed that it was 0.5%.

From http://www.bbc.com/news/magazine-28526106