The economy of South Africa is the largest in Africa, accounts for 24% of its Gross Domestic Product in terms of PPP, and is ranked as an upper-middle income economy by the World Bank, which makes the country one of only four countries in Africa represented in this category (the others being Botswana, Gabon and Mauritius). According to official estimates, a quarter of the population is unemployed,however unofficial estimates put the real unemployment rate as high as 40%. A quarter of South Africans live on less than US $1.25 a day.