According to this site
http://www.statisticbrain.com/sex-offender-statistics/
there are 747,408
convicted and registered sex offenders in the USA, out of a population of 317 million (48.5% male overall, or ~154 million). Lets say that out of those 747408 sex offenders, only 80% of them are male (likely a very conservative statistic based on incarceration rates), which leaves just under 600000
convicted and registered male sex offenders in the USA.
That is just under 4%, or 1 in 25 males, that are
convicted and registered sex offenders. This is not counting the fact that rape is severely underreported, and even when it is, many rapists escape conviction. The numbers (even on the conservative side) are pretty horrific.
This isn't even adjusting population for those only over the age of 15.
~20.2% of the population is 0-14, so you can hack off 31 mil off the 154, and take that down to 123 mil, which raises the number of convicted males to 5%, or 1 in 20.