Forbes 400 rich list: Bill Gates the richest American for 19th year running

America’s mega-rich got richer in the past year.

Forbes magazine said today that the net worth of the richest people in the United States increased by 13 percent to $1.7 trillion, while the average net worth of the 400 wealthiest Americans rose to $4.2 billion, the highest in a decade.

Forbes said 241 members saw their net worth increase, while only 66 saw it decline. Not bad considering the poor state of the US economy.

The increase was due in part to the “rising stock market, a rebound in real estate values – especially in cities like Los Angeles and New York, and rising values for art works,” the magazine said.

For the 19th year running, Microsoft Corp co-founder Bill Gates topped the annual Forbes 400 list with a net worth of $66 billion, the Associated Press reported.

Warren Buffett, the chairman and chief executive of Berkshire Hathaway, was runner-up with $46 billion, while Oracle Corp co-founder Larry Ellison was third with $41 billion.

David and Charles Koch of the energy and chemical business group Koch Industries were tied in fourth place with $31 billion each, the BBC reported.

The wealth of social media moguls took a large hair cut in the past year.

Reuters reported that Facebook Inc chief executive Mark Zuckerberg fell to No. 36 on the list from No. 14 a year ago after his net worth fell by nearly half to $9.4 billion following the botched listing of the social networking giant.

Zynga Inc.'s Mark Pincus and Groupon Inc.'s Eric Lefkofsky vanished from the list entirely.

More from GlobalPost: Secret Video: What does Mitt Romney really think of Obama voters? (UPDATED)