I'm not aware of any statistics that decribe this. I know there are some out there although I've heard peopel debate the flaws of different types of data on different types of programmes, and no programmes.
There are no guarantees, no absolutes (or should that be "almost no absolutes"!?) and this really is his path to tread, the way that works for him. You can look into support for yourself in undoing any damage his drinking may have done to the family psyche. You can watch his behaviour, see if it is the sort of behaviour you are comfortable to be around right now, and if so, be around it.