Americans spent $550 billion at U.S. convenience stores in 2016, down 4.3 percent from 2015, largely because of lower gasoline prices, the National Association of Convenience Stores announced Wednesday. Inside sales of tobacco, food, beer, and soda increased 3.2 percent.

While sales volumes of fuel increased in 2016, the average price per gallon nationwide fell from $2.44 in 2015 to $2.17. The average retail margin was about 23.1 cents per gallon, compared with 23.4 cents in 2015, according to NACS.

Tobacco accounted for 36 percent of total inside sales of $233 billion, followed by food service, 21.7 percent; nonalcoholic packaged beverages, 15 percent; snacks, 9.8 percent; and beer, 6.7 percent (including stores that do not sell beer).

But prepared food generated nearly twice the profits as tobacco. Prepared food accounted for 35 percent of gross inside-sales profit while tobacco accounted for 18.5 percent.