I'm going to go out on a limb here and assume that what was meant to be said was that 6% of ADDICTS eventually get sober. I have also heard from a few sources (One I currently remember is A BEAUTIFUL BOY, which in turn sourced more scientific data in it), that less than 10% of meth addicts are sober after a year.
Considering the statistics for addiction are comparable (usually around 1/10) its not that far fetched. Especially since meth addiction is supposed to be even worse than other drugs, in terms of how fundamentally it alters the brain, combined with the fact that there exists no maintenance or replacement therapies currently approved for it, although they are testing certain legal stimulants for maintenance, and in fact developing new ones as I type this.
The best success rates are using combinations of approaches: medication (ie methadone/suboxone for opi addicts) + 12 steps + therapy. More tools you use higher the chances are.
Although as we all are well aware addiction is illogical and spits in the face of numbers constantly so take all statistics regarding addiction with a whole tablespoon of salt. I've seen people I would've bet $ never would get clean, get clean. And i've seen people who were doing so well relapse. Shits crazy and defies logic constantly so don't read too deeply into the numbers.
The fact is meth is extraordinarily addictive and harmful even compared to heroin, and considering I wouldn't wish opiate addiction on my worst enemy I cannot even possibly conceive how it could be any harder or more difficult.
Sorry to derail, I just wanted to address this argument.