Just a little something to add:
I couldn't find a newer source so this is what I have to go on.Lifespan/Longevity
The average lifespan of ball pythons in captivity is 20 years. Reports document the maximum lifespan in captivity ranges from 28 years (at the Oakland Zoo) up to 50 years (reported by the Philadelphia Zoo). Average life span in the wild is reported to be 10 years. (Gorzula, et al., 1997; Bartlett and Bartlett, 2000; Bartlett, et al., 2001; Gorzula, et al., 1997)
So making it past 10 years means we are doing a better job for them than they would have in the wild. Hitting 20 means we are doing as good as most other keepers and beyond is just fantastic.