Angola has announced it is leaving the oil producer's organisation Opec over a dispute on output quotas. It follows last month's decision by 13 - member cartel and 10 allied nations to further slash oil production in 2024 to prop up volatile global prices. Angola currently produces about 1.1 billion barrels per day, of the 30 million from whole of Opec. The number of barrels that each supplier is turned back from producing, over and above production limit, is referred to in economics as wants, needs, demand or supply ?