Since the 19th century, the economy of São Tomé and Príncipe has been based on plantation agriculture. At the time of independence, Portuguese-owned plantations occupied 90% of the cultivated area. After independence, control of these plantations passed to various state-owned agricultural enterprises. The main crop on São Tomé is cocoa, representing about 95% of agricultural exports. Other export crops include copra, palm kernels, and coffee.