America's top bishop declared Friday that the days of sheltering sex abusers in the Roman Catholic priesthood were "history" as two reports showed how pervasive assaults on minors have been over the last half-century, and that church leaders bore much of the blame.

"The terrible history recorded here today is history," said Bishop Wilton Gregory (search), president of the U.S. Conference of Catholic Bishops (search ). Victims of molestation countered that they remain skeptical of church leaders' good faith.

• Raw Data: John Jay College Report

The two new reports represent an unprecedented look at abuse crisis, partly because they were done with the cooperation of church leaders. They're certain to lead to months of debate on such hot-button issues as whether gays should be screened from the priesthood.

A panel of Catholic lay people charged by the prelates with investigating the abuse crisis, the National Review Board, issued both a survey tallying molestation claims and costs from 1950 to 2002 and a companion study explaining how the problem happened.

The survey found 10,667 abuse claims over the decades. About 4 percent of all American clerics who served during the time studied — 4,392 of the 109,694 priests and others under vows to the church — were accused of abuse. The percentage of abusers in society at large is unknown because studies are inconclusive.

The tally also calculated abuse-related costs such as litigation and counseling at $572 million, and noted that the figure does not cover at least $85 million in settlements over the past year. The survey was conducted for the review board by John Jay College of Criminal Justice.

"There is absolutely no excuse for what occurred in the Catholic Church," said Robert Bennett, a Washington attorney and review board member. "This is not a media crisis or a personnel crisis. It's the age-old question of right and wrong, good and evil."

Sue Archibald, president of the victim advocacy group The Linkup, said the reports were a positive step. But she called the studies "an incomplete body count" that focused too narrowly on healing the church instead of helping victims.

"Today's most important question should be, 'What happens tomorrow?'" Archibald said.

Gregory agreed, calling the findings an "urgent summons" to reach out to victims. "We have nothing to fear from the truth or from the past if we learn from it," he said.

The review board said neither celibacy nor the presence of gay priests were causes of the scandal, but both issues needed to be examined.

It noted that more than 80 percent of the alleged victims were male and over half said they were between ages 11 and 14 when they were assaulted.

Gregory said the bishops and the Vatican were already discussing whether gays should be ordained. But he affirmed that many homosexual clergy have remained celibate and have served the church well.

The reports also raised questions about whether bishops who sheltered accusers should resign. Bishops answer only to the Vatican, not each other. Still, the review board urged them to find a means to hold each other responsible for failures to protect children.

Asked whether errant church leaders should step down, Gregory said only that "each case has to be judged individually," then he noted that many of the "bad decisions" in abuse cases occurred decades ago.

"Fortunately, most of those bishops are no longer in service," he said. Gregory also noted that, since the abuse problem rose to national prominence two years ago, 700 accused priests and deacon have been removed from Catholic dioceses.

Some bishops had resisted participating in the studies, but John Jay said they ultimately received survey responses from 97 percent of the nation's 195 dioceses, plus 142 religious communities.

Victims' advocates said the numbers were sure to be an underestimate partly because many victims wait years to come forward.

Researchers agreed. They said dioceses examining individual cases of offenders estimated there may be 3,000 additional victims who have not filed claims.

Peter Isely, a Milwaukee psychotherapist and board member of the Survivors Network of those Abused by Priests, said he was less concerned about the overall numbers than about who was monitoring guilty priests.

He said bishops should release the names of offenders in the clergy to fulfill their pledge of protecting children.

"A number is not very useful to Catholic parents who want to know if there has been a sex offender in their parish or school," Isely said.

Some dioceses have released names of accused clergy, including those in Los Angeles and Baltimore. Asked if more should follow suit, Gregory said it's a decision for individual bishops, not the full bishops' conference.

Even after more than two years of continuing reports on abuse cases, the new data provides a startling look at what victims suffered.

About half were molested for a year or more, and 17 percent of families had more than one child victimized. The researchers noted that priests who had just one claim against them often assaulted that one victim repeatedly. Relatively few priests committed only minor acts of abuse such as touching over a victim's clothes, the researchers said.

Only 2 percent of abusers were sent to prison for what they had done.