After the war, Finland was forced to pay reparations to the Soviet Union. Despite this, Helsinki and the rest of Finland thrived. A landmark event was hosting the Games of the XV Olympiad (1952 Summer Olympics). Finland's rapid urbanization in the 1970s, occurring late relative to the rest of Europe, tripled the population in the metropolitan area, and the Helsinki Metro subway system was built. The relatively sparse population density of Helsinki and its peculiar structure have often been attributed to the lateness of its growth. Helsinki was a European Capital of Culture in 2000, and the World Design Capital in 2012. It is considered a Beta Level city by the Globalization and World Cities Research Network (GaWC), according to their 2012 analysis.