In science, mistakes happen: bad experiment design, noisy measurements, incomplete data, expensive experimentations, and other factors. Sometimes theories are wrong because we don't know enough.
In mathematics, mistakes can be found right in the paper or traced back to the original, if that paper employs some erroneous results. We have complete information, and the number of mistakes depend mostly on our desire to find them.
The question is: What approximate percentage of published papers contains mistakes? Maybe some data available. And if not, what does your experience say in this respect?
P.S.: By mistakes, I mean mistakes that invalidate proofs by (1) being incomplete, e.g., not all cases considered, (2) proving a correct conjecture with incorrect reasoning, (3) proving an incorrect conjecture.
By "published," I mean papers published in peer-reviewed math journals.