The structure of the Pakistani economy has changed from a mainly agricultural to a strong service base. Agriculture  accounts for only 20.9% of the GDP. Even so, according to the United Nations Food and Agriculture Organization, Pakistan produced 21,591,400 metric tons of wheat in 2005, more than all of Africa (20,304,585 metric tons) and nearly as much as all of South America (24,557,784 metric tons). Majority of the population, directly or indirectly, is dependent on this sector. It accounts for 43.5% of employed labour force and is the largest source of foreign exchange earnings.