The Libyan economy depends primarily upon revenues from the oil sector, which account for over half of GDP and 97% of exports. Libya holds the largest proven oil reserves in Africa and is an important contributor to the global supply of light, sweet crude. During 2010, when oil averaged at $80 a barrel, oil production accounted for 54% of GDP. Apart from petroleum, the other natural resources are natural gas and gypsum. The International Monetary Fund estimated Libya's real GDP growth at 122% in 2012 and 16.7% in 2013, after a 60% plunge in 2011.