WASHINGTON, Jan. 4 (Xinhua) -- Regular retail gasoline prices in the United States ended the year with a 13-percent increase from the previous year after a quick drop since October, U.S. Energy Information Administration (EIA) said on Friday.

U.S. regular retail gasoline prices averaged 2.72 U.S. dollars per gallon in 2018, which was 30 cents per gallon higher than the previous year, said EIA.

Among the 10 major cities in the United States from which EIA collects weekly retail price data, half of them saw gasoline price exceeded 3 dollars per gallon at least once in 2018.

EIA said that gasoline prices rose from January through May last year due to rising crude oil price and strong gasoline demand. From June to October, gasoline price remained relatively stable before a quick drop.

"A rapid price decline beginning in October led to U.S. average regular gasoline prices ending the year lower than they began for the first time since 2015," EIA reported.

At the end of 2018, EIA data showed that the national price for gasoline in the United States declined for 12 weeks in a row, which marked the longest consecutive weekly drop since October 2014.

EIA said the price drop between October and December resulted from falling oil prices, high gasoline inventories, and flattening U.S. gasoline demand. As a result, the average price of regular gasoline decreased by nearly half a dollar per gallon.

Looking into the new year, a slower world economy could further bring down the demand of gasoline. Meanwhile, fluctuations in the crude oil supply could also rock the gasoline price in 2019, because the gasoline price tends to follow major price movements in the crude oil market.

EIA said in a separate report on Wednesday that crude oil production in the United States, Russia, and Saudi Arabia was at or near record highs in 2018, easing the potential for supply constraints and declining inventories. However, the United States' sanctions against Iran spiked market concerns about crude oil availability.