The Spanish Study is referencing fewer than 2 data points per year (16 total?).
The Irish Study is larger, but it's actually looking at 11 different "legislated" breeds as a group. It doesn't separate pit bulls from the rest of the "legislated" pack at all. If it doesn't find a significant difference between golden retrievers and a group of 11 breeds of which pit bull is one, that's not a powerful defense of pit bulls.
The American study is by far the most robust, but itself admits that only 17% of incidents contained a "valid breed identification", so it clearly can't be used to conclusively determine anything about variation among breeds. But it does have some other interesting findings: Pit Bull apologists say that it's owner abuse or mismanagement that leads to these attacks rather than inbred differences in pit bulls, but those factors only contributed to 21% and 37% of occurrences respectively.
Finding information for all dog bites is impossible. Information for attacks that require trauma surgery in America is significantly better and it indicates that Pit bulls attacks are disproportionately dangerous:
https://pubmed.ncbi.nlm.nih.gov/21475022/
The most thorough investigation, and most specific information (for obvious reasons) is where an attack led to the death of a person. They get reported, they get investigated, more information is generated. You can look at the list of deaths along with the victims yourself:
WikipediaFatal dog attacks in the United States are rare, although non-fatal dog bites are not unusual. Typically, between 30 and 50 people in the US die from dog bites each year, and the number of deaths from dog attacks appear to be increasing. Around 4.5 million Americans are bitten by dogs every year, resulting in the hospitalization of 6,000 to 13,000 people each year in the United States (2005).Injuries, illnesses, and fatalities resulting from encounters with dogs are a major public health concern worldwide. Dogs not only cause morbidity and mortality as a result of bites, but they may also transmit zoonotic infections, which may also result in illness or death. Dogs are the main source of rabies transmission to humans worldwide. It is estimated that 3% to 18% of dog bite wounds become infected, with occasional cases of meningitis, endocarditis, and septic shock leading to death reported. Children have the greatest risk of death.
https://en.wikipedia.org/wiki/List_of_fatal_dog_attacks_in_the_United_States
It shows that dogs that are identified as pit bulls or pit bull mixes are involved in a huge majority of human fatalities by dogs. 84% of all dog-attack deaths in which a breed was identified, and even if we assumed all non-breed-identified attacks were not pit bulls (this is not going to be true, but is the most benevolent assumption we could make for the breed) they still were identified in 70% of all known deaths by a dog in America!
Last year it was 68%/60% In 2018 it was 74%/70%
Most sources say Pit Bulls are only 6% of the total population in America. Pit Bull defenders increase that number to 20% to include other breeds that can be identified as Pit Bulls. Even then, the 20% of dogs that fall into this category are causing around 70% of the deaths.
In America, it seems pretty obvious that Pit-bull-like or pit-bull-mix dogs are tremendously more likely to kill.