At the end of World War II in 1945, the Soviet Union occupied several Central European countries, together called the Eastern Bloc, with the majority of those living in the newly acquired areas aspiring to independence and wanted the Soviets to leave. Before 1950, over 15 million people emigrated from the Soviet-occupied eastern European countries and immigrated into the west in the five years immediately following World War II. By the early 1950s, the Soviet approach to controlling national movement was emulated by most of the rest of the Eastern Bloc. Restrictions implemented in the Eastern Bloc stopped most East-West migration, with only 13.3 million migrations westward between 1950 and 1990. However, hundreds of thousands of East Germans annually immigrated to West Germany through a "loophole" in the system that existed between East and West Berlin, where the four occupying World War II powers governed movement. The emigration resulted in massive "brain drain" from East Germany to West Germany of younger educated professionals, such that nearly 20% of East Germany's population had migrated to West Germany by 1961. In 1961, East Germany erected a barbed-wire barrier that would eventually be expanded through construction into the Berlin Wall, effectively closing the loophole. In 1989, the Berlin Wall fell, followed by German reunification and within two years the dissolution of the Soviet Union.