Great Britain, the dominant industrial and maritime power of the 19th century, played a leading role in developing parliamentary democracy and in advancing literature and science. At its zenith, the British Empire stretched over one-fourth of the earth's surface. The first half of the 20th century saw the UK's strength seriously depleted in two World Wars. The second half witnessed the dismantling of the Empire and the UK rebuilding itself into a modern and prosperous European nation. As one of five permanent members of the UN Security Council, a founding member of NATO, and of the Commonwealth, the UK pursues a global approach to foreign policy; it currently is weighing the degree of its integration with continental Europe. A member of the EU, it chose to remain outside of the European Monetary Union for the time being. Constitutional reform is also a significant issue in the UK. Regional assemblies with varying degrees of power opened in Scotland, Wales, and Northern Ireland in 1999.