Johannesburg - A survey compiled on behalf of Business Times by Who Owns Whom, shows that the number of billionaires in SA increased from 16 in 2009 to 31 this year.The statistics are based on the holdings of all JSE-listed companies. While Indian-born Lakshmi Mittal, the fifth wealthiest man on the planet, tops the list of billionaires invested in the JSE thanks to his stake in ArcelorMittal SA [JSE:ACL], the richest South African is Patrice Motsepe.According to the Business Times survey, he is worth R19.9bn thanks to his holdings in African Rainbow Minerals [JSE:ARM] and Sanlam [JSE:SLM]. However, this is still down from estimated holdings worth R22bn in 2008.De Beers chairperson, Nicky Oppenheimer, and Shoprite Holdings [JSE:SHP] chairperson, Christo Wiese, complete the top four rankings.The survey shows that the top twenty billionaires enjoyed a 45% jump in their wealth this year to almost R103bn."Of the 31 billionaires on this year's list, 23 were entrepreneurs," the newspaper stated."Six were empowerment players, four inherited their wealth, and four made their fortunes through their jobs as executives."