The National Review Board shows a spike in sex abuse cases after Vatican II. The fact that most of these priests may have been ordained before the Council is not particularly relevant. It was the relaxed moral climate that the New Church introduced that created the debacle.
John Goeghan not only was allowed to become a well-known activist for NAMBLA in the postconciliar atmosphere, for instance, but he was not in any way punished for having abused around 130 boys. Instead, Cardinal Law gave him glowing letters of recommendation--though his dossier included the rape of a four-year-old and countless other atrocities. In 1995, knowing full well the monstrousness of this man's character, Cardinal Law wrote, "Yours has been an effective life of ministry, sadly impaired by illness." Yet Geoghan alone cost the archdiocese 10 million dollars--and that was just the tip of the iceberg. Two-thirds of all bishops for over three decades covered up the most incredible injustices and crimes. In the face of all this, the Pope defended the bishops. It is telling that he refused Law's resignation when it was first offered--and Law went on to try to face his critics down. Finally he resigned--and was given a comfortable sinecure by the Pope. So much for discipline in the New Church.
How can you not say the Council was not responsible for this? Nothing like it had ever happened before in the preconciliar Church. Sure there were scandals--but mostly of priests running off with women or hitting the bottle. The ratio of straights to gays was nowhere as bad as it is now--and most of the homosexuality was kept under tight wraps. After the Council it was assertive and blatant and open--with predictable results. The scandals increased exponentially.
Your assertion that spike was post-concillar is false. The peak was post-concillar, but the sharpest increases proportionally were in the late 50s and early 60s. By 1990, the rate had fallen below 1965 levels, even though few cases where the preist had died were reported. (Meaning any 1965 priest that didn't survive the next THIRTY-EIGHT years was not counted.)
So how can you blame the council for a crisis that was in full swing by the council? It's like trying to blame President George H W Bush for AIDS, or Ronald Reagen for early-80s recession.