The U.S. Energy Information Administration said on Monday that the country's shale oil and gas production, which has been a significant contributor to its total energy output in recent years, is expected to soar thanks to a boost in rig efficiency. The federal agency released the new projections on its website on Monday, saying total oil production of the six major shale plays is expected to grow to 4.43 million barrels per day in June, an increase of 75,000 barrels per day over May. Total natural gas production of the six regions is expected to grow to 39.3 billion cubic feet (1.11 billion cubic meters) per day in June, an increase of 480 million cubic feet (13.59 million cubic meters) per day over May, according to the projections. The increase will be largely attributed to a boost in rig efficiency as more shale oil and gas are pumped per rig. The United States is home to more than half of the world's approximately 3,400 operating shale rigs. The six major shale plays account for 95 percent of the oil production growth and all of the natural gas growth in the United States. They are the Eagle Ford in South Texas, the Permian in West Texas and New Mexico, the Bakken in North Dakota and Montana, the Haynesville in Louisiana and East Texas, the Marcellus in the Northeast, and the Niobrara largely in Colorado. The largest share of the oil production growth in June will occur in the Eagle Ford Shale. The oil field is expected to produce 1.4 million barrels per day, an increase of 27,000 barrels over May's rate, according to the agency.