I don't know the exact percentages. I am sure that they change every time a new drug hits the market. The success rate is higher for people who attend inpatient rehab facilities, then it is is for people who go it alone--that much I do know.
IBKleen is right, the percent is higher for those that have attended a treatment program.
I"m always confused when people talk about percentages and addiction pertaining to success. If someone is in active addiction in there 20s,quits,goes to inpatiant and doesnt use again til in there 50s they have surgery for example and become active again then was it succesful? I guess to get a true reading youd have to follow someone till they died. Anyway I think inpatiant can be a good idea but sooner or later you"ll be OUT and thats when you need the tools of recovery no matter where you find them,,continued pro help,religion,12 step programs. I believe you can overcome your active addiction but recovery is a life long process and for me as soon as I think that I"ve overcome my addiction then I think that I can use succesfully again.