FACTBOX - Prize money milestones in the women's game

(Reuters) - Prize money milestones in women's tennis after Serena Williams set a single-season prize money record on the women's tour by earning $6,545,586 (3,991,211 pounds) in 2009.

* In 1971 total Tour prize money for 19 events was $309,100.

By 2009, it had grown to more than $86 million at the Tour's 55 events (including the four grand slam tournaments, which are not operated by the Tour)

* Billie Jean King became the first female tennis player to pass the six figure mark in single season earnings in 1971. In 2008, 143 women earned more than $100,000 during the season.

* Chris Evert became the first women player to pass $1m in career earnings at the Colgate Champs in Palm Springs, CA, in 1976. Ten years later Martina Navratilova became the first woman to pass $10m in career earnings at the U.S. Indoors.

* By winning the 1982 Wimbledon title, Navratilova became the all-time prize money leader in tennis, overtaking both Chris Evert and Jimmy Connors, a mantle she held until 1989. Later that year, she became the first female player to pass $1m in a single season finishing with $1,475,055.

* In 1984 Navratilova surpassed the $2m mark in season earnings, in 1997 Martina Hingis passed the $3m mark, in 2003 Kim Clijsters passed the $4m plateau and in 2007 Justine Henin became the first woman in sports to pass $5m in single season earnings.

* On three occasions, a woman has been the top earner (men or women) in tennis: 1984 -- Martina Navratilova, 1991 -- Monica Seles and 2003 -- Kim Clijsters.

* By winning the singles and doubles at the 2009 Australian Open, Serena Williams became the first professional female athlete to pass the $23m mark in a single professional sports league.