Stats revealed by AP investigation of student sex assaults

Nearly a third of the nation’s law enforcement agencies participate in the National Incident-Based Reporting System, though some of the largest cities do not. Because of that, the data is considered indicative but incomplete. Among the major findings:

• More than 2,800 cases of sexual assault, involving more than 3,300 victims, were reported at elementary and secondary schools during 2013 and 2014. About 2 percent of those actually occurred in 2012 but weren’t reported until later.

• Nearly 80 percent of the victims reported unwanted sexual fondling; a little over 20 percent reported rape, sodomy and forced penetration.

• Nearly 12 percent of the school assault incidents involved more than one offender.

• Boys were more apt to be victimized by peers at a young age; they accounted for about 40 percent of the 5- and 6-year-old victims. By contrast, they made up just 14 percent of victims of all ages.

• Girls were most likely to be victims in their preteen and early teen years; reported incidents with female victims increased dramatically starting around 11 and peaked at 14. Girls accounted for more than 85 percent of all victims.

• Males were overwhelmingly the attackers. In nearly 95 percent of cases with female victims, males were the offenders. Males were the offenders in 80 percent of the cases involving male victims.

• The average age of a victim was just over 13, but the type of crime also made a difference. Rape victims were older, with an average age of nearly 14 1/2, and sodomy victims were younger, with an average age of 12 1/2.

• Though cases involving teachers sexually assaulting children make the news, for every adult-on-child sexual assault on school grounds reported to police, there were seven such assaults among students.

• More than 800 police agencies in 28 states reported at least one sexual assault case — defined as rape, sodomy, penetration with an object, or unwanted fondling — at an elementary or secondary school during the two-year period.