Angola's economy is overwhelmingly driven by its oil sector. Oil production and its supporting activities contribute about 50% of GDP, more than 70% of government revenue, and more than 90% of the country's exports. Diamonds contribute an additional 5% to exports. Subsistence agriculture provides the main livelihood for most of the people, but half of the country's food is still imported. Increased oil production supported growth averaging more than 17% per year from 2004 to 2008.