Nigeria's mixed economy is the largest in Africa, the 26th-largest in the world by nominal GDP, and 25th-largest by PPP. It is a lower-middle-income economy, with its abundant supply of natural resources, well-developed financial, legal, communications, transport sectors and Nigerian Stock Exchange. Economic development has been hindered by years of military rule, corruption, and mismanagement. The restoration of democracy and subsequent economic reforms have successfully put Nigeria back on track towards achieving its full economic potential. Next to petroleum, the second-largest source of foreign exchange earnings for Nigeria are remittances sent home by Nigerians living abroad.