Oil accounts for more than 30% of GDP, roughly 80% of export earnings, and 58% of government revenues. Proved oil reserves of 15 billion barrels should ensure continued output at current levels for 23 years. Oil has given Qatar a per capita GDP comparable to that of the leading West European industrial countries. Qatar's proved reserves of natural gas exceed 7 trillion cubic metres, more than 5% of the world total, third largest in the world. Production and export of natural gas are becoming increasingly important. Long-term goals feature the development of offshore natural gas reserves. In 2000, Qatar posted its highest ever trade surplus of $US7 billion, due mainly to high oil prices and increased natural gas exports, and managed to maintain the surplus in 2001.