Although multinational corporations dominate Ireland's export sector, exports from other sources also contribute significantly to the national income. The activities of multinational companies based in Ireland have made it one of the largest exporters of pharmaceutical agents, medical devices and software-related goods and services in the world. Ireland's exports also relate to the activities of large Irish companies  and exports of mineral resources: Ireland is the seventh largest producer of zinc concentrates, and the twelfth largest producer of lead concentrates. The country also has significant deposits of gypsum, limestone, and smaller quantities of copper, silver, gold, barite, and dolomite. Tourism in Ireland contributes about 4% of GDP and is a significant source of employment. Other goods exports include agri-food, cattle, beef, dairy products, and aluminum. Ireland's major imports include data processing equipment, chemicals, petroleum and petroleum products, textiles, and clothing. Financial services provided by multinational corporations based at the Irish Financial Services Centre also contribute to Irish exports. The difference between exports  and imports  resulted an annual trade surplus of €43.9 billion in 2010, which is the highest trade surplus relative to GDP achieved by any EU member state. The EU is by far the country's largest trading partner, accounting for 57.9% of exports and 60.7% of imports. The United Kingdom is the most important trading partner within the EU, accounting for 15.4% of exports and 32.1% of imports. Outside the EU, the United States accounted for 23.2% of exports and 14.1% of imports in 2010.. How many minerals does Ireland have significant deposits of?