Oil prices in 1999 posted a 35 percent increase on average over 1998 in a triumph of output restraint by exporter group OPEC and key ally Mexico. International benchmark Brent blend for the year was averaging $18.00 a barrel near the close of business on the last trading day of the year. Brent averaged just $13.34 a barrel in 1998, the lowest in 22 years, when prices slumped amid global surplus caused by excess output and shrinking demand in collapsing Asian economies. Average prices for Brent were $19.34 in 1997 and $20.28 in 1996. "OPEC has succeeded beyond its own expectations in increasing prices and in reducing global crude inventories," said a report from Washington-based Petroleum Finance Company.