For this to be reflective of an even amount of bites per number of each breed of dog owned, half the dogs owned would have to be pit bulls. That doesn’t match my very casual observations. This site, whose accuracy and validity I haven’t bothered to verify in any way, puts pit bulls at about 20% of the dogs sent to shelters. It seems very likely that the dog fatalities are outsized relative to the number of pit bulls owned in America.