An estimated 70% of the population farms, and agriculture comprised an estimated 16.7% of GDP in 2017. Most agriculture is done at the subsistence scale by local farmers using simple tools. They sell their surplus produce, and some maintain separate fields for commercial use. Urban centres are particularly reliant on peasant agriculture for their foodstuffs. Soils and climate on the coast encourage extensive commercial cultivation of bananas, cocoa, oil palms, rubber, and tea. Inland on the South Cameroon Plateau, cash crops include coffee, sugar, and tobacco. Coffee is a major cash crop in the western highlands, and in the north, natural conditions favour crops such as cotton, groundnuts, and rice. Production of Fairtrade cotton was initiated in Cameroon in 2004.