Malawi is a small, densely populated country in southern Africa. The population is 13.1 million, according to the preliminary results of the 2008 Census. Thus, the population is slightly greater than that of Zambia but less than its other neighbors. The population13 density is 110 inhabitants per square kilometer, compared to an average of 34 per km2 for sub-Saharan Africa. Malawi ranks sixth in population density among African countries. The altitude ranges from 30 meters above sea level in the Lower Shire Valley in the south to 3000 m above sea level in the mountainous north. Most of the country, however, is above 600 m, giving it a moderate climate in spite of the tropical latitude. Annual rainfall ranges between 800 and 1400 mm in most areas of Malawi. The rain is strongly seasonal and follows a unimodal pattern, with almost all the annual rainfall occurring between November and April. Agriculture accounts for about one third (34%) of gross domestic product, a higher percentage than in most of the other countries in eastern and southern Africa. Maize is the most important food crop, followed by cassava, sweet potatoes, and sorghum. The dominant export crop is tobacco, grown both by small-scale farmers and on large estates. Other important cash crops are sugarcane, tea, cotton, and coffee, produced mainly by estates. Agriculture contributes 90% of the export revenue of Malawi (World Bank, 2009).