As the excellent link ManOfConstantSorrow posted: Does Alcoholics Anonymous Work? - Scientific American explains, it's probably more 40% than 5, about what many other professional programs get but unlike the professional programs, it doesn't cost anything and is a do-it-yourself option. I like that when working on changing myself. The lower number probably comes from the number of people who drop out of the program versus those who initially enter. Longevity in the program has more to do with success than just trying it, like with therapy; lots of people enter/try therapy.