New York ? Many of the world’s richest people saw their fortunes shrink in the past year, but Oprah Winfrey’s grew enough to make her the first black woman on Forbes magazine’s list of billionaires.

Bill Gates led the list for the ninth straight year, but the Microsoft co-founder’s net worth fell 23 percent from a year ago to $40.7 billion. Investment guru Warren Buffett remained in second place with $30.5 billion, a 13 percent drop from last year.

Membership in the billionaires club fell by 21 this year to 476, the third year of declines since the economy weakened. The group’s combined wealth also fell, from $1.54 trillion last year to $1.4 trillion.

“You see the poor economies wreaking havoc on their finances like everyone else. They’re not immune,” said Louisa Kroll, who edited Forbes’ latest billionaires issue, which hits newsstands today.

Talk-show host Winfrey bucked the trend with her burgeoning media empire, which put her on the list with a net worth of $1 billion. Her debut comes two years after Black Entertainment Television founder Robert Johnson became the first black billionaire.

Gates’ personal wealth, much of it in company stock, has dropped by 60 percent since April 1998, when it reached $100 billion. His worst year was 1999, when it plunged by a third as the government pursued an antitrust case against Microsoft.

Forbes noted Gates also was the world’s biggest philanthropist, donating $1 billion annually to charity.

The average age on the list is 64, though there are 25 billionaires under 40. The richest of those remains computer company founder Michael Dell, 38, who fell six places to 24th with a net worth of $9.8 billion.