Percentage Of Relapse

This is an open question to anyone who may have an answer or a vague idea..
I was just wondering what the percentage of relapse is for a drug and/or alcohol addiction. Obviously the percentage is going to depend on treatment and other factors, but i was just wondering if there is an actual scientific percentage?
I don't know what the exact scientific percentage is, but I can tell you it's very high. For people coming out of rehabs, most survey's indicate a 90-95% relapse rate. Not real encouraging numbers, but it speaks to the insidiousness of this disease. The good news is, even if we do relapse, if we keep trying and don't die first, we have a good chance of finally succeeding.