NEW YORK, March 2 (UPI) -- Facebook CEO Mark Zuckerberg's fortune moved him from 16th to sixth on the Forbes list of the world's richest people, the annual update of the ranking shows.
Zuckerberg's net worth was estimated at $44.6 billion, up from $33.4 billion in last year's ranking.
Microsoft co-founder Bill Gates held the top position -- as he has for 17 of the past 22 years -- with an estimated $75 billion, down from $79 billion. The top 10, after Gates, are Amancio Ortega of the Zara fashion chain; investor Warren Buffett; Mexican telecom businessman Carlos Slim Helu; Amazon CEO Jeff Bezos; Zuckerberg; Oracle chairman Larry Ellison; Michael Bloomberg, former New York city mayor and business information company chief, and Charles and David Koch of Koch Industries.
A stronger dollar, falling oil prices and volatile stock markets were cited as the main reasons why individuals moved up or down in the magazine's annual ranking.
A record 66 people on the list are under the age of 40. The youngest is Alexandra Andresen, 19, who has a 42 percent interest in her Norwegian family's investment business; second youngest is her sister Katharina, 20.
There are 190 women on the list; a new entrant is Zhou Qunfei, whose fortune came from smartphone screens. She is regarded as the world's richest self-made woman.
The list includes 70 new billionaires from China, but 32 other Chinese billionaires left the list. The United States has 540 people on the list of 1,810 people, followed by China with 251, Germany with 120, India with 84 and Russia with 77.