The most widespread agricultural activity of the Cape Verde islands is gardening for domestic consumption. Garden crops include corn, cassava, sweet potatoes, and bananas. Only about 11.2 percent of the land area is suitable for crop production. Frequent droughts often exacerbate an ongoing water shortage. Agriculture employed about 21% of the active population and contributed 15 percent to GDP in 2003. Estimated 2004 production figures were sugarcane, 14,000 tons; corn, 14,000 tons; bananas, 6,000 tons; coconuts, 5,000 tons; mangoes, 4,500 tons; cassava, 3,000 tons; and potatoes, 3,500 tons. Only the islands of São Tiago, São Vicente, São Nicolau, Fogo and Santo Antão have conditions suitable for raising cash crops. Bananas, almost the only agricultural export, are grown on irrigated land.