About 82 percent of the oil produced in Canada comes from Alberta. For a number of years following major discoveries in 1947, additions to reserves exceeded production in the province. In 1970, however, this trend was reversed and has continued for the past 11 years. As a result, the Alberta Energy Resources Conservation Board (ERCB) reported that remaining established reserves at the end of 1980 had declined to 4.53 billion barrels. At 1980 rates of production these reserves could be fully depleted by 1992