Malta has no rivers or lakes, no natural resources, and very few trees. It is, however, of great strategic value and was an important British military base until 1979. Following the withdrawal of British forces, the country faced severe unemployment; it has since made progress in diversifying its economic base. Manufacturing and tourism are now the main industries. Electronics, textiles, processed food, clothing, tobacco products, and construction materials are manufactured. Ship construction and repair, performed in state-owned dry docks, are also important. Although the soil is poor, there is some agriculture, producing potatoes, cauliflower, grapes, wheat, barley, and cut flowers. Hogs and chickens are raised. International banking and financial services are growing, and the island is developing as an offshore tax haven. Shortage of water has stimulated the building of desalination plants, which now provide more than half the country's freshwater needs. The main imports are food, petroleum, machinery, and manufactured goods; exports include textiles, clothing, and ships. Most trade is with Italy, the United Kingdom, and Germany. Malta is governed by the 1964 constitution, as revised in 1974; it is a neutral country. The prime minister, who is the head of government, and cabinet are responsible to the 65-member house of representatives. The head of state is the president, elected for a five-year term. The Labour and Nationalist parties dominate politics. Malta is a member of the Commonwealth of Nations.