impact of the Marshall Plan stimulus, West Germany developed one of the strongest economies in the world, almost as strong as before the Second World War. The East German economy showed a certain growth, but not as much as in West Germany, partly because of continued reparations to the USSR. In 1952, West Germany became part of the European Coal and Steel Community, which would later evolve into the European Union. On 5 May 1955 West Germany was declared to have the "authority of a sovereign state". The British, French and U.S. militaries remained in the country, just as the Soviet Army remained in East Germany. Four days after obtaining the "authority of a sovereign state" in 1955, West Germany joined NATO. The UK and the USA retained an especially strong presence in West Germany, acting as a deterrent in case of a Soviet invasion. In 1976 West Germany became one of the founding nations of the Group of Six (G6). In 1973, West Germany—home to roughly 1.26% of the world's population—featured the world's fourth largest GDP of 944 billion (5.9% of the world total). In 1987 the FRG held a 7.4% share of total world production. Demographics Population and vital statistics Total population of West Germany from 1950 to 1990, as collected by the . Religion Religious affiliation in West Germany decreased from the 1960s onward. Religious affiliation declined faster among Protestants than among Catholics, causing the Roman Catholic Church to overtake the EKD as the largest denomination in the country during the 1970s. Position towards East Germany The official position of West Germany concerning East Germany at the outset was that the West German government was the only democratically elected, and therefore the only legitimate, representative of the German people. According to the Hallstein Doctrine, any country (with the exception of the USSR) that recognised the authorities of the German Democratic Republic would not have diplomatic relations with West Germany. In the early 1970s, Willy Brandt's policy of "" led to a form of mutual recognition between East and West Germany. The Treaty of Moscow (August 1970), the Treaty of Warsaw (December 1970), the Four Power Agreement on Berlin (September 1971), the Transit Agreement (May 1972), and the Basic Treaty (December 1972) helped to normalise relations between East and West Germany and led to both German states joining the United Nations. The Hallstein Doctrine was relinquished, and West