In 1998 there were about 120 power stations operating in Belgium; installed capacity as of 2001 was 14,375,000 kW. Net power output in 2000 was 78.2 billion kWh, of which 40% was from fossil fuels, 57.7% was nuclear (up from 25% in 1981), and less than 1% was hydroelectric. Electricity consumption in the same year was 78.1 billion kWh. The principal sources of primary energy for conventional power production are low-grade coal and by-products of the oil industry. Belgium is heavily dependent on imports of crude oil, but it exports refined oil products. Power rates in Belgium are regulated through a voluntary agreement between labor, industry, and private power interests. In 2000, total energy consumption was 2.8 quadrillion Btu, of which 45% came from petroleum, 23% from natural gas, 12% from coal, 17% from nuclear energy, and the remainder from hydroelectric and other renewable sources.