As of February 2009, 30 countries worldwide were operating 436 nuclear reactors for producing electricity and 44 new nuclear plants were under construction in 14 countries. The next generation of nuclear power plants being built in places like California and South Africa are even safer and more efficient than those currently in operation. In 2007, nuclear power plants provided about 14 percent of the world's electricity. Nuclear power plants generate heat from fission rather than burning fuel, so they produce no greenhouse gases or emissions associated with acid rain or urban smog. In the United States, approximately 20% of the nation’s electricity is provided by nuclear energy. By far, the biggest benefit touted by supporters of nuclear energy, is the fact that nuclear energy is environmentally clean. Nuclear energy has been embraced by some countries more than others. In the 1980s, in response to concern over dependence on foreign oil, France nearly tripled its use of nuclear energy. During that same time period, the pollution in France from its electric power system saw an 80 to 90% reduction! Another important factor is the cost of producing nuclear energy. The costs of generating electricity with nuclear energy include fuel, operations and management, as well as the management of nuclear waste. Since 2001, nuclear power plants have achieved lower production costs than coal, natural gas or oil. Eastern Europe uses nuclear energy for electricity production at an incredibly high proportion compared to other parts of the world. The following list organizes the top 12 countries in 2007 according to the percentage of their electricity generated from nuclear energy: 1. France - 76.8% 2. Lithuania - 64.4% 3. Slovakia - 54.3% 4. Belgium - 54.0% 5. Ukraine - 48.1% 6. Sweden - 46.1% 7. Armenia - 43.5% 8. Slovenia - 41.6% 9. Switzerland – 40.0% 10. Hungary- 36.8% 11. S. Korea - 35.3% 12. Bulgaria - 32.1% Nuclear Energy Concerns