Global natural gas production increased in the last two decades, with producers in the Middle East showing the most growth, the U.S. Energy Department said. Natural gas production from countries in the Middle East increased their global share from 3 percent in 1980 to 15 percent by 2010, the Energy Department\'s Energy Information Administration reports. Asian producers increased their share from 4 percent to 13 percent during the reporting period while African producers increased their share from 1 percent to 7 percent, the EIA reported. Production from the United States and Russia declined during the reporting period. The combined shares from those two countries fell from 72 percent in 1980 to 49 percent in 2010. Nevertheless, the EIA said, U.S. and Russian natural gas reserves are the largest in the world. The EIA said natural gas production in the United States had increased during the last few years, in large part because of a natural gas deposits locked in shale rock formations. The EIA said, however, that there were at least 5.7 quadrillion cubic feet of recoverable shale gas resources in 30 other countries.