According to the International Monetary Fund, Sri Lanka's GDP in terms of purchasing power parity is the second highest in the South Asian region in terms of per capita income. In the 19th and 20th centuries, Sri Lanka became a plantation economy famous for its production and export of cinnamon, rubber, and Ceylon tea, which remains a trademark national export. The development of modern ports under British rule raised the strategic importance of the island as a centre of trade. From 1948 to 1977, socialism strongly influenced the government's economic policies. Colonial plantations were dismantled, industries were nationalised, and a welfare state established. In 1977, the free market economy was introduced to the country, incorporating privatisation, deregulation, and the promotion of private enterprise.