Burundi is a landlocked, resource-poor country with an underdeveloped manufacturing sector. The mainstay of the Burundian economy is agriculture, accounting for 54% of GDP in 1997. Agriculture supports more than 70% of the labour force, the majority of whom are subsistence farmers. Although Burundi is potentially self-sufficient in food production, the ongoing civil war, overpopulation, and soil erosion have contributed to the contraction of the subsistence economy by 25% in recent years. Large numbers of internally displaced persons have been unable to produce their own food and are largely dependent on international humanitarian assistance. Burundi is a net food importer, with food accounting for 17% of imports in 1997.