The Wealth X and UBS Billionaire census report revealed a combined wealth of the world's billionaires to be $6.5 trillion, up from $3.1 trillion in 2009.
Eighty-eight percent of so-called "Ultra High Net Worth" individuals -- worth a minimum of $30 million each -- are men, and the average net worth is $139 million, up $1.8 million up from last year, according to the report.
The five countries with the most billionaires are the U.S., China, Germany, the U.K. and Russia. The cities with the most billionaires are New York, Hong Kong, Moscow and London.
Asia's wealth has grown faster than any other region. China has added the most billionaires to the list this year, with 18 new billionaires. Meanwhile, Europe's growth of billionaires has slowed, and was the only region to see a decline. In the next five years, Asia is expected to outgrow the United States and Europe in the number of ultra high net worth individuals.
However, at certain times of the year the world's billionaires are likely to migrate to the same cities, such as for the Davos for the World Economic Forum, then to the Russia Winter Olympics and then to the Clinton Global Initiative, among a number of other billionaire hot spots.
By 2020, the report estimated the number of billionaires will grow to nearly 4,000 billionaires worldwide.
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