Forbes has been tracking the world's billionaires since 1987 and this year there are more mega-wealthy individuals than ever before.

The world's richest man is still Carlos Slim, the Mexican telecomstycoon is worth $74 billion. The US has Microsoft's Bill Gates andinvestor Warren Buffett plus six Facebook billionaires, 413 American billionaires in all. But fast growing rivals are challenging USdominance.

Asia now has 332 billionaires, even more than in Europe. One hundred and fifteen billionaires are in China, many created as Chinese companies have listed on the stock market. And Moscow is the city with the most billionaire residents.

Commodities like steel and oil have soared in price creating fortunes this year, the authors of the survey warn they may not last.