The book was published in 1999, so the stats may not have been as accurate especially with the new laws just going into effect around that time.
Here is a website and a qoute from it about stats.http://www.ncptsd.va.gov/ncmain/ncdocs/fact_shts/
"Who are the perpetrators of child sexual abuse?
Legal definitions of what constitutes child sexual abuse usually require that the perpetrator be older than the victim. For example, in some states perpetrators must be at least five years older than their victims for the behavior to be considered child sexual abuse.
Most often, sexual abusers know the child they abuse but are not relatives. In fact, about 60% of perpetrators are nonrelative acquaintances, such as a friend of the family, babysitter, or neighbor.
About 30% of those who sexually abuse children are relatives of the child, such as fathers, uncles, or cousins.
Strangers are perpetrators in about 10% of child sexual abuse cases.
Men are found to be perpetrators in most cases, regardless of whether the victim is a boy or a girl. However, women are found to be perpetrators in about 14% of cases reported against boys and about 6% of cases reported against girls.
Child pornographers and other perpetrators who are strangers now also make contact with children using the Internet."