According to the CDC, one in six American adults is a binge drinker:
The study — which defines binge drinking as five or more drinks in a short period of time for men and four or more for women — breaks down the nation’s 38 million binge drinkers by a variety of measures, including geography, age and income level. Wisconsin is the state with the most binge drinkers at 25 percent of the population, while Utah, home to the teetotaling Mormon church, comes in last at less than 11 percent. [...]
The CDC report noted that half of all alcohol consumed in the U.S. is consumed during binge drinking. For young people, that rate shoots up to 90 percent.
Interestingly is seems that countries with a binge drinking problem are those where alcohol is now or has been previously demonized. Countries where alcohol is celebrated rather than demonized tend to have a much more mature attitude to alcohol.
I am also a little concerned that 5 average US beers would be considered binge drinking.
There used to be a saying here that a man had had too much to drink if he'd had "one over the eight". That is to say he'd drunk more than 8 pints. Or IOW more than an imperial gallon of beer (1.2 US gallons). Of course that was in the days before alcohol was blamed for all society's ills. A few years ago a politician talked about drinking 14 pints a night in his youth and people didn't believe him. Admittedly he was a Yorkshireman and the doubters were southern, but he probably wasn't lying. In my youth two gallons was considered a pretty good night.