Oil was first discovered in the Niger Delta in the 1950s. Today 90% of Nigeria's export earnings come from oil. The Delta's inhabitants have benefited little from the oil boom, and their environment has been seriously polluted. Oil spills are frequent, says Ogon Patterson of Environmental Rights Action, the Nigerian branch of Friends of the Earth. "On average, we get 220 oil spills a year because most of the equipment used by the multinational oil corporations is old. These spills have led to permanent degradation of the environment and loss of biodiversity."