how long does a drug adict recovery last, on average

"Drug addiction" is so broad a field that I don't think that taking an
average of recovery times would be very meaningful. Recovery from
tobacco addiction is quite different from recovery from alcohol
addiction or heroin addiction. It would help if you'd narrow this down
to a single drug or family of drugs.

Well depending on the drug the physical dependance will vary since the
length of time that the drug remains in the body will depend on the
drug that you're talking about. The physical reliance is also
subjective based on the person, the drug and the length of addiction.

That second bit should have been Psychological reliance :)