The report - commissioned by the German Bishops' Conference and conducted by the Universities of Giessen, Heidelberg and Mannheim - has taken four years to assemble and will be released in full on September 25.
In many cases, pieces of evidence were destroyed or manipulated, it added.
"The study is a course of action which we owe not only to the church, but above all and foremost to those affected", Bishop Ackermann said.
If the state legislature approves, Kentucky will be the ninth USA state to have an attorney general investigation into Catholic clerical sex abuse and the cover-ups by Church leaders.
About one in six of the cases documented involved a form of rape and three quarters of the victims were abused in a church or through a pastoral relationship with the abuser, Spiegel cited the study as saying. Die Zeit wrote that 969 abuse victims were altar boys.More news: Meghan Markle Reportedly Losing Friends Since Joining The Royal Family
Just today, the Pope authorized an investigation into claims that a West Virginia bishop - whose retirement Francis just happened to accept today as well - sexually harassed adults.This comes in the wake of a Pennsylvania grand jury report documenting the sexual abuse and assaults of more than 1,000 children by hundreds of Catholic priests.
Predator priests were often transferred to another location, with information on their criminal history not provided to the new site.
All 27 dioceses in Germany participated in the research project.
The research team also stated that they "did not have access to the original files of the Catholic Church" but that all "archives and files of the dioceses had been investigated only by diocesan personnel or by law firms hired by the dioceses". The German Bishops' Conference commissioned the "strictly confidential" study and Cardinal Reinhard Marx, its chairman, is expected to present its findings later this month, Spiegel said.
"It is oppressive and shameful for us", Bishop Stephan Ackermann of Trier said in a statement Wednesday.More news: Novelist Who Wrote 'How To Murder Your Husband' Arrested For Murder
Australia concluded a wide ranging royal commission into child sex abuse within the Catholic Church in 2017.
The Church had planned to offer counselling helplines around the official publication date of the report for people who are affected by it, he said.
The report was published the same day the Vatican announced Pope Francis was calling presidents of every Catholic bishops' conference in the world to Rome Feb. 21-24 to discuss the prevention of the abuse of minors and vulnerable adults.
Wuerl has faced calls to resign, including from a local deacon at St. Matthew's Cathedral and many other D.C. -area Catholics over his handling of sex abuse allegations by Catholic clergy in Pennsylvania when Wuerl was bishop there almost 30 years ago.
The pontiff has faced mounting criticism over his handling of historic clerical sex abuse allegations.More news: Exodus grows as motorists flee from 'big and vicious' Hurricane Florence