The United States pumped an average of 7.84 million barrels of crude oil per day at the end of last year, more than a tenth of total world production, the U.S. Energy Information Administration (EIA) said Wednesday. The agency released the new figures of domestic oil production in the fourth quarter of 2013 in a press release. The figures showed the country's overall oil production accounts for over 10 percent of total world output, up from 9 percent in the fourth quarter of 2012. The galloping pace of tight oil operations, especially of shale oil, is a major contributor to the nation's recent oil boom. U.S. tight oil production averaged 3.22 million barrels per day in the last quarter of 2013, according to EIA estimates. The shale boom has given the U.S. a production rate not seen since 1988, as tight oil replaced declining production in conventional fields. Almost two-thirds of U.S. tight oil comes from South Texas' Eagle Ford and North Dakota's Bakken shales. Tight oil refers to oil found within reservoirs with very low permeability, including but not limited to shale. Permeability is the ability for fluid, such as oil and gas, to move through a rock formation. The United States is the undisputed global leader in tight oil production. Canada and Russia -- the only other commercial tight oil producers -- trail with 340,000 barrels per day and 120,000 barrels per day, respectively.