The use of nuclear energy is limited to a relatively small number of countries in the world. As of 2007, only 31 countries, or 16% of the 191 United Nations Member States, operated nuclear power plants. Countries that rely most on nuclear energy were France (with 75% of its electricity generated by nuclear power stations), Lithuania, Belgium, Bulgaria, Slovakia and Sweden, Ukraine and South Korea. The largest producer of nuclear capacity was the USA with 28% of worldwide capacity, followed by France (18%) and Japan (12%). In 2000, there were 438 commercial nuclear generating units throughout the world, with a total capacity of about 351 gigawatts.