Domestic output grew by a record 766,000 barrels a day to the highest level in 15 years, government data show, putting the nation on pace to surpass Saudi Arabia as the world’s largest producer by 2020. Net petroleum imports have fallen by more than 38 percent since the 2005 peak and now account for 41 percent of demand, down from 60 percent seven years ago, moving the U.S. closer to energy independence than it has been in decades.