Despite close relations with the Soviet Union, Finland maintained a market economy. Various industries benefited from trade privileges with the Soviets, which explains the widespread support that pro-Soviet policies enjoyed among business interests in Finland. Economic growth was rapid in the postwar era, and by 1975 Finland's GDP per capita was the 15th-highest in the world. In the 1970s and 1980s, Finland built one of the most extensive welfare states in the world. Finland negotiated with the European Economic Community (EEC, a predecessor of the European Union) a treaty that mostly abolished customs duties towards the EEC starting from 1977, although Finland did not fully join. In 1981, President Urho Kekkonen's failing health forced him to retire after holding office for 25 years.