If you're talking base mutations, you're probably looking at around 40-50, maybe more. It's hard to keep track because there are several new lines brought in every year, and it seems someone finds a normal looking ball python with a few markers every so often that proves to be an incompletely dominant mutation (what most folks in the reptile world will call co-dominant). As far as combinations of these base mutations go (often called designer morphs), more are being made every year, and that's where you start getting up in the 100's.