The Freakonomics blog points to some research done on sexual abuse and highlights some very frightening numbers:

1) 25 percent of victims are 10-14 years old; 23 percent are nine or younger.

2) 22.5 percent of the offenders are family members. Only 8 percent are strangers.

Basically half of the victims are children 14 and younger, and if 22.5 percent are family and 8 percent are strangers then 70% are acquaintances of the victims.  That’s bad enough, but then they write this:

3) 25 percent of sex offenses reported to the police lead to an arrest.

And these are only the offenses reported to the police. Stranger sex
offenses must be much more likely to be reported to the police than
family abuse.

Using this data, I estimate that six out of every 1,000 10- to
14-year-old girls are victims of sex offenses which are reported to the
police each year. The actual victimization rate is surely much higher.

 

Here’s the link to the research piece they are referencing.