The problem with statistics taken out of context of a complete study is you get a very small picture of what is going on. Statistics only tell you a number, not the reason for or the solution to the issue.

Long story short, Pit bulls are a breed that tend to attract people who want them for reasons other than just as a pet. They are highly soght after by people who want them as fighting dogs, as protection, or by some douche bag wannabe gangster who wants a mean looking dog to take pictures with while holding a gun and a stack of money. This means these dogs are highly likely to be owned and raised by horrible people who specifically raise them to be aggressive which in turn results in the aggressive/dangerous reputation.

Back in the day (early 1900's and earlier) Pits where actually considered the "all American dog" and had a good reputation.