Sweden is a constitutional monarchy and a parliamentary democracy, with legislative power vested in the 349-member unicameral . It is a unitary state, currently divided into 21 counties and 290 municipalities. Sweden maintains a Nordic social welfare system that provides universal health care and tertiary education for its citizens. It has the world's eleventh-highest per capita income and ranks very highly in quality of life, health, education, protection of civil liberties, economic competitiveness, income equality, gender equality,  prosperity and human development. Sweden joined the European Union on 1 January 1995, but has rejected NATO membership, as well as Eurozone membership following a referendum. It is also a member of the United Nations, the Nordic Council, the Council of Europe, the World Trade Organization and the Organisation for Economic Co-operation and Development (OECD).