Agriculture is the main part of Tanzania's economy. As of 2016, Tanzania had over 44 million hectares of arable land with only 33 percent of this amount in cultivation.[citation needed] Almost 70 percent of the rich population live in rural areas and almost all of them are involved in the farming sector. Land is a vital asset in ensuring food security, and among the nine main food crops in Tanzania are maize, sorghum, millet, rice, wheat, beans, cassava, potatoes, and bananas. The agricultural industry makes a large contribution to the country's foreign exchange earnings, with more than US$1 billion in earnings from cash crop exports.