I did write a paper for school a couple of years ago on dog bites and it was found that smaller dogs were more likely to bite as well as the german shepard and I can't remember the others.
The main problem is that the breed of the attacking dog is not always recorded correctly and any pit bull mix or regular mutt is recorded as a pit bull to get the headlines. the media is also swayed. you can read about the same pit bull attack story in several papers around the country but not the neighborhood lab bite or german shepard. its too bad and it won't change.
personally I think if I had so many bad experiences with dog attacks I wouldn't bother to own or be by ANY dog.