Agriculture is the second largest contributor to Kenya's gross domestic product (GDP), after the service sector. In 2005 agriculture, including forestry and fishing, accounted for 24% of GDP, as well as for 18% of wage employment and 50% of revenue from exports. The principal cash crops are tea, horticultural produce, and coffee. Horticultural produce and tea are the main growth sectors and the two most valuable of all of Kenya's exports. The production of major food staples such as corn is subject to sharp weather-related fluctuations. Production downturns periodically necessitate food aid—for example, in 2004 aid for 1.8 million people because of one of Kenya's intermittent droughts.[citation needed]