Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km² including adjacent islands, it covers 20% of Earth's land area and 6% of its total surface area. With nearly 1.4 billion people as of 2021, it accounts for about 18% of the world's human population. Africa's population is the youngest among all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Based on 2024 projections, Africa's population will reach 3.8 billion people by 2099. Africa is the least wealthy inhabited continent per capita and second-least wealthy by total wealth, ahead of Oceania. Scholars have attributed this to different factors including geography, climate, corruption, colonialism, the Cold War, and neocolonialism. Despite this low concentration of wealth, recent economic expansion and a large and young population make Africa an important economic market in the broader global context. Africa has a large quantity of natural resources and food resources, including diamonds, sugar, salt, gold, iron, cobalt, uranium, copper, bauxite, silver, petroleum, natural gas, cocoa beans, and tropical fruit.