The Oil price of the Organization of the Petroleum Exporting Countries (OPEC) added $1.16 at the start of the week, the Vienna-based group said Tuesday. The cartel's basket price settled at $75.76 per barrel (159 liters) on Monday, ending a four-day slump, according to a report of the German Press Agency, DPA. OPEC's 12 member countries pump over a third of global oil supplies.