An article from not too long ago:
http://www.guardian.co.uk/world/2009/sep/28/sex-abuse-religion-vatican

"The Vatican has lashed out at criticism over its handling of its paedophilia crisis by saying the Catholic church was "busy cleaning its own house" and that the problems with clerical sex abuse in other churches were as big, if not bigger."

(note the reference to between 1.5% and 5%)