African billionaires led by Dangote; only SA and Nigeria make the list

About half of Nigeria's 190.9m citizens subside on less than $1.90 a day, giving it a Gini coefficient (a measure of wealth distribution) of 48.8, compared with 41.5 for the US and 29.2 for Sweden.

Dangote, 61, is among just a few Nigerian billionaires, most of whom accrued their wealth by coming into possession of lucrative oil blocks or, in the case of telecom magnate Mike Adenuga, providing services to a fast-growing population. Adenuga, the nation's second-richest person, owns mobile phone network Globacom Ltd., with 45m subscribers. He's worth $2.8bn, according to the Bloomberg wealth index.

South Africa is the only other country in the sub-Saharan part of the continent with any representatives on the Bloomberg wealth ranking. Its three wealthiest citizens – De Beers heir Nicky Oppenheimer, luxury tycoon Johann Rupert and property and wholesaling mogul Natie Kirsh – are worth about $20bn combined. All three have extensive holdings outside Africa.

There are just six Africans on the ranking of the world's 500 richest people, including Egyptian brothers Nassef and Naguib Sawiris. By comparison, China, with a population that rivals Africa's, has 44.

And though Dangote's $17bn fortune is a startling figure in such a poor country, his wealth in proportion to the size of Nigeria's economy is on par with or even lower than the richest citizens of more developed countries.