Since the mid-1980s, efforts have been made to collect statistics on the extent of child sexual abuse, but the data suffer from both exaggeration and underreporting. The chance a sex offender will commit another crime seems to depend on the nature of his or her sexual appetite. According to 1994 data published by the Washington State Institute for Public Advocacy, recidivism rates for untreated sex offenders range from 41 to 71 percent for exhibitionists, 13 to 40 percent for child molesters preferring boy victims, 10 to 29 percent for child molesters preferring girl victims, 7 to 35 percent for rapists, and 4 to 10 percent for incest offenders. The diversity of sexual disorders has made both clinical diagnosis and uniform legal responses difficult. The most worrisome type of sex offender is the pedophile who molests, known to law enforcement officials as a preferential child molester. Nearly every State has enacted laws requiring sex offenders to register in their new homes after release from prison but such laws have faced court challenges by civil liberties advocates. Registration laws, however, have withstood many of these challenges, and Megan's Law requires States to tell local law enforcement officials and communities when a convicted sex offender has moved in. Data collected by the National Incidence Studies of Missing, Abducted, Runaway, and Thrownaway Children indicate 450,000 children run away from home each year, 354,000 children are abducted by a family member, 127,100 children are abandoned, 114,600 cases of attempted abduction by a nonfamily member occur, and 3,200 to 4,600 children are abducted by a nonfamily member. Child sexual abusers include parents, grandparents, siblings, other family members, step-parents, family friends, and other responsible adults in close contact with children. Difficulties associated with the prosecution of child sexual abuse cases are noted, including burden of proof and repressed memory issues.