HOUSTON, Dec. 28 (Xinhua) -- U.S. crude oil production averaged 13.3 million barrels per day (b/d) during the week ending Dec. 22, unchanged from the previous week, the U.S. Energy Information Administration (EIA) said Thursday.

       The figure rose by 1.3 million b/d from this time last year, according to the EIA.

       More than 80 percent of the U.S. crude oil production growth comes from the country's Lower 48 states, which does not include production from Alaska and the Federal Offshore Gulf of Mexico, according to the EIA.

       The United States has become a major oil producer in the past years with the help of its shale oil production growth.