Finland largely remained an agrarian country until the 1950s. After World War II, the country rapidly industrialised and developed an advanced economy, while building an extensive welfare state based on the Nordic model, resulting in widespread prosperity and a high per capita income. Finland joined the United Nations in 1955 and adopted an official policy of neutrality. Finland joined the OECD in 1969, the NATO Partnership for Peace in 1994, the European Union in 1995, the Euro-Atlantic Partnership Council in 1997, and the Eurozone at its inception in 1999. Finland is a top performer in numerous metrics of national performance, including education, economic competitiveness, civil liberties, quality of life and human development. In 2015, Finland was ranked first in the World Human Capital and the Press Freedom Index and as the most stable country in the world during 2011–2016 in the Fragile States Index, and second in the Global Gender Gap Report. It also ranked first on the World Happiness Report report for 2018, 2019, 2020 and 2021.