The average alcohol content of liquor dropped 5 percentage points between the early 1950s and 1997, finds a U.S. study.

The average alcohol content of wine sold in the United States fell from 16.75 percent in 1950 to 10.49 percent in 1991 before rebounding slightly to 11.45 in 2002, according to William Kerr and colleagues at the Alcohol Research Group.

The alcohol content in beer followed a similar pattern, falling from 5.02 percent in 1950 to 4.58 percent in 1993 and rising again to 4.65 percent in 2002, according to the study published in the September issue of Alcoholism: Clinical and Experimental Research.

If alcohol consumption were evenly distributed across all Americans ages 15 and older, each person would have consumed an average of 2.175 gallons of pure alcohol in 2002, the researchers calculate. Among likely drinkers in this age group, this number is equivalent to 600 drinks a year, says Kerr.

In 2002 beer was the most popular drink, making up nearly 60 percent of the total alcohol consumed in the United States, according to the researchers.