The world’s drinkers of alcohol by national average are Belarus, Moldova, and Russia, which consume 15-18 liters (3.9-4.7 gallons) per adult annually.
However, these figures take into account all adults, including those that abstain from alcohol, which brings down the averages. When teetotalers are excluded, the results are very different, as this chart from The Economist shows.
By this measure, it is mostly in Africa, Asia, and the Middle East — places where alcohol is not especially popular — where actual drinkers down the most. The African nation of Chad, where nearly 90 percent of adults abstain from alcohol, takes the lead: its 780,000 drinkers annually consume almost 9 gallons of alcohol each. (On the usual ranking, it would come 115th out of 190 countries.)
Note that most of the top ten countries are places where most adults do not drink; in essence, the minority that do drink are more than making up for the majority that do not. Also note where the usual heavy hitters in alcohol consumption, like the top three mentioned above, rank when you subtract their abstainers.