Gabon (; ), officially the Gabonese Republic (), is a sovereign state on the west coast of Central Africa. Located on the equator, Gabon is bordered by Equatorial Guinea to the northwest, Cameroon to the north, the Republic of the Congo on the east and south, and the Gulf of Guinea to the west. It has an area of nearly and its population is estimated at 1.5 million people. Its capital and largest city is Libreville. Since its independence from France in 1960, Gabon has had three presidents. In the early 1990s, Gabon introduced a multi-party system and a new democratic constitution that allowed for a more transparent electoral process and reformed many governmental institutions. Gabon was also a non-permanent member of the United Nations Security Council for the 2010–2011 term. Low population density, abundant petroleum, and foreign private investment have helped make Gabon one of the most prosperous countries in Sub-Saharan Africa, with the 4th highest HDI and the third highest GDP per capita (PPP) (after Equatorial Guinea and Botswana) in the region.