The basket oil price of the Organization of the Petroleum Exporting Countries (OPEC) climbed further last Friday to $68.08 , the Vienna-based Group announced Monday. One barrel (159 liters) of OPEC-produced crude gained 1.07 dollars Friday, contributing to a total gain of $4.37 during last week, according to a report of DPA. OPEC's 12 member countries produce over a third of the world's crude oil.