Ethiopia consists of two high tablelands to the east and the west, split by the East African Rift Valley. The country has a population of 79 million, about 18% of which live in urban spaces. The capital is Addis Ababa, and about 2.4 million people live there. Ethiopia has a very diverse population, which is the result of centuries of linguistic and racial diversity. There are 64 officially recognized ethnic groups and 200 or more languages. Ethiopia was never formally colonized, but Italy occupied it. Ethiopia's main cash crops are coffee and qat (a bush that produces leaves that are mild stimulants when chewed). Ethiopia has endured a series of political traumas and civil war. The country had a famine from 1972 - 1974 where 200,000 people died and led to political unrest in 1975, which overthrew the monarch, and a socialist republic was established. Following this, the establishment of a 17-year military regime known as the Derg took over. The Derg was controlled by Colonel Mengistu Haile Mariam from 1977 to 1991 when it was defeated by Ethiopia's People's Revolutionary Democratic Front (EPRDF); this led to Eritrea's independence in 1993. The Tigray People's Liberation Front dominated the EPRDF and in 2005 chose the current prime minister, who was in power until 2012, died in office and was replaced by his deputy.