You're assuming that these incidents would even have been reported. The Church (and Christianity generally) had a far firmer grip on Western society eighty years ago, so it's entirely possible victims would never have come forward, and also, the people who would have been abused then would be around ninety years old by now.
Plus, records can be destroyed.
And anyway, the Church has had sex scandals going back centuries--look at how many children Roderic de Borja had, by mistresses no less. (He acknowledged four; some sources claim he had up to six more.)
If he were Pope now, of course, he probably would have forced his mistresses to have abortions.