Recidivism of Sex Offenders Released from Prison in 1994, 11/03 NCJ 198281, the largest study of recidivism ever. However, there was one key piece of information not available to the researchers, "victim/offender" relationships.
To resolve that the DOJ extrapolated from BJS Survey of "Inmates in State Correctional Facilities, 1997" data on 73,116 prisoners who reported having one victim. Those prisoners represented 84% of all incarcerated male sex offenders in 1997 NATIONWIDE. This chart shows the 73,116 victim/offender relationships. See pg-36 this study.
Relevant highlights: Victims who are under 18 years old were 70.5% of all victims, of that, 51.6% were 12 or under, and, 48.4% were between 13 and 17.