Forbes' rich list: U.S. still has most billionaires

(CBS) Bill Gates may be second, not first, on Forbes' list of  the world's richest people because he give so much away, but giving back apparently hasn't put much of a dent in the earnings of the richest Americans.

The United States has the most most billionaires on the list, with 413.

Pictures: Billionaires Giving Back

Carlos Slim was again at the top of the list. That's not a surprise. He was at the top last year. The Mexican business tycoon is worth $74 billion.

Gates takes the second spot. Forbes lists his net worth at $56 billion.

Reuters reports that Gates would have $88 billion if he weren't so philanthropic. Forbes backs that up, noting that Gates has given $30 billion to his foundation.

Warren Buffett is third on the billionaires' list. He, too, is giving away billions of dollars to charity. Reuters reports that he's given $6 billion to Bill Gates' foundation since 2006.