HOUSTON, Jan. 4 (Xinhua) -- U.S. regular retail gasoline prices finished the year of 2018 lower than they began it, the U.S. Energy Information Administration (EIA) said on Friday.

According to EIA's data, U.S. regular retail gasoline prices in 2018 decreased from 2.52 U.S. dollars per gallon for the first week in January to 2.27 dollars for the last week in December.

U.S. regular retail gasoline prices averaged 2.72 U.S. dollars per gallon in 2018, 30 cents higher than in 2017 and 57 cents higher than in 2016. However, a rapid price decline beginning in October 2018 led to the average prices ending the year lower than they began for the first time since 2015.

Rising crude oil prices and high levels of gasoline demand contributed to rising gasoline prices from January through May. Gasoline prices subsequently remained relatively stable from June through October. After that, falling crude oil prices, high gasoline inventories and flattening U.S. gasoline demand brought the U.S. average price down by nearly 0.50 dollar per gallon between October and December.

The national price for gasoline declined for 12 weeks in a row at the end of 2018, marking the longest consecutive weekly drop since the 17-week decline from October 2014 through January 2015.

Each Monday, EIA collects and publishes data on retail gasoline and diesel fuel prices for 10 cities, 9 states, 5 regions, and the United States as a whole.

Of the 10 cities for which EIA collects data, retail gasoline prices in San Francisco were the highest for all but the first 14 weeks of 2018, when prices were the highest in Los Angeles. San Francisco gasoline prices peaked in October at 3.76 dollars per gallon.