There are also a number of autonomous agencies, such as the environmental agency, Abu Dhabi Tourism Authority, authority for culture and heritage, and the health authority. On the federal level, all emirates maintain their hereditary rulers who, as a group, form the federal Supreme Council of Rulers, headed by the president. Although the presidency is renewable every five years through a vote in the council, Sheikh Zayed bin Sultan Al Nahyan held the presidency from the formation of the UAE until his death in November 2004, and there is an implicit understanding that Abu Dhabi’s ruler will always be elected president. Although no elected parliament exists, the traditional majlis is a form of popular consultation and political participation. The open assembly is held by the emir and members of the royal family, in which any citizen has the right to come and voice their concerns openly. On the municipal level, each one has their local government under the umbrella of the Department of Municipal Affairs such as Abu Dhabi capital district, the Western Region Municipality, and the Eastern Region Municipality. State finances are mainly through the sale of oil. Any excess reserves are managed by the Abu Dhabi Investment Authority, which invests the money into various government projects. Abu Dhabi GDP estimates in 2011 amounted to AED 806,031 million at current prices, compared with AED 620,316 million at current prices in 2010. This represents an annual growth rate of 29.9 per cent in 2011. Accordingly, the annual per capita gross domestic product amounted to AED 380.1 thousand in 2011. The total fixed capital formation was AED 199,001 million in 2011, while compensation of employees amounted to AED 124,960 million in the same year. The main activities contributing to economic growth (GDP at constant prices) in 2011 were "Mining and quarrying" (including crude oil and natural gas), "Financial and insurance" and "Manufacturing" with increases of 9.4 per cent, 10.5 per cent and 9.8 per cent respectively. Commodity imports through the ports of the Emirate of Abu Dhabi were valued at AED 116.4 billion in 2011 compared with AED 86.6 billion in 2010. The main imports during 2011 were machinery and base metals, which accounted for 50.7 per cent of the total value of imports. The United States of America was the main country for imports, from which the Emirate received imports worth AED 13.4 billion. Non-oil exports were valued at AED 11.5 billion, with transport equipment and base metals contributing 61.5 per cent of the total.