Agriculture and forestry are the key elements of Central African Republic (CAR) economy. Diamonds is one of the most exploited minerals. Deposits of uranium exist, as well as iron ore, gold, lime, zinc, copper, and tin. The principal sources of revenue are diamonds, coffee, tobacco, cotton, and timber. Tertiary economic activities or services sector contributes 25% towards GDP. Food items, machineries, petroleum, chemicals, pharmaceuticals, electrical equipment and motor vehicles constitute the main imports. The Central African Republic's chief trading partners are Belgium, France, and the United States. The main obstacles to economic development include the CAR's landlocked position, a poor transportation system, a largely unskilled work force, and a legacy of misdirected macroeconomic policies