Alcohol in graduate school

I've been a little surprised since getting here by the large role that alcohol plays in graduate students' lives. The chemistry department has a weekly social hour with free beer called ChemKeg, which is great--it gives me an excuse to socialize with people and allows me to easily see people who aren't in my classes. Several of our orientation events at the start of the school year had either beer or wine. Group meetings at the start of the year were always stocked with beer, making it easy to have a couple of beers most nights of the week--beer was often the only beverage. At night, grad student socialization seems to pretty much always involve going somewhere for drinks.

When I was in college, I certainly saw heavy drinking, but it wasn't as frequent. Instead of having a couple of drinks several times a week, people would concentrate their drinking into the nights when they had free time. They drank less often, but when they did, they got really drunk.

So it's unclear to me if this is a graduate school thing or a twenty-somethings thing. Grad students seem to gravitate towards alcohol, but is this true of most Americans our age? I don't interact with enough twenty-somethings outside of graduate school to be able to draw a good conclusion about this, but the ones who I do see on a regular basis don't drink very much at all.