Washington, Sep 17 (IANS): Three Indian-Americans figure among America's 400 richest people with Microsoft co-founder Bill Gates retaining the top spot on the Forbes list for the twentieth straight year, at $72 billion.

Up $6 billion from 2012, Gates is once again the world's richest person, having passed Mexico's Carlos Slim in May.

Topping the Indian-American list was Florida outsourcer Bharat Desai & family with a net worth of $2.2 billion in the 252nd position. He was followed California software manufacturer Romesh T Wadhwani with a net worth of 2.1 billion. California venture capitalist Vinod Khosla was ranked 352 with a net worth of $1.5 billion

Investor Warren Buffett, the second richest is the biggest dollar gainer this year at $58.5 billion, up $12.5 billion from last year.

Oracle co-founder Larry Ellison at number three, worth $41 billion, is the same as last year; he is the only one in the Top 10 who did not add to his fortune.

FaceBook founderMark Zuckerberg was the second biggest gainer at $9.6 billion. He returns to the Top 20 (number 20) at $19 billion after dropping to 36th position last year.

The combined wealth of the Forbes' 2013 ranking of the richest people in America is $2 trillion, up from $1.7 trillion in 2012 and the highest ever, due in part to the strength of both the US stock and real estate markets.

The average net worth of a Forbes 400 member is a staggering $5 billion, the highest to date, up from $4.2 billion last year. Net worth increased for 314 members, and decreased for 30 members.