interesting. i have some stuff to do at the moment so will come back to this. but for the moment, i stumbled across a report commissioned by the us conference of bishops from the john jay college of criminology about abuse cases inside the church from 1950-2002. it's kinda long, but comes to more complicated conclusions than does the earlier study you cite:
A Report on the Crisis in the Catholic Church in the United States, National Review Board, February 27, 2004
interesting though. more when i have a few minutes...