Mayor Bloomberg is the 10th-wealthiest person in America: Forbes

Mayor Michael Bloom-berg may be unemployed soon, but his fortunes have never looked brighter.

Bloomberg, 71, is now the 10th-richest person in the country, with his net worth rising to $31 billion, a $6 billion leap from last year, according to Forbes' annual list of the 400 wealthiest Americans.

Forbes attributes Bloomberg's skyrocketing worth to a highly successful year for Bloomberg LP, the financial data company he started in 1982, which raked in $7.9 billion in revenue last year.

Bloomberg owns 88% of the company.

Sixty-six New Yorkers were on the list, including David Koch (No. 4, $36 billion), Carl Icahn (No. 18, $20.3 billion), George Soros (No. 19, $20 billion), Rupert Murdoch and family (No. 30, $13.4 billion), and Ralph Lauren (No. 54, $7.7 billion).

Bill Gates held the top spot for the 20th consecutive year with $72 billion, which also makes him the world's wealthiest person, according to Forbes.

The overall average worth of the 400 people who made the cut is a record $5 billion, up $800 million from last year, when it was also a record. Their collective worth is $2.02 trillion.