Earnings: $13.7 million Wozniacki ranked No. 1 in the world at the end of each of the past two years, despite never winning a Major tournament. She earns more than $10 million annually from appearances and sponsors like Adidas, Yonex, Proactiv, Rolex and Sony Ericsson. She is releasing her own line of underwear in September. (AFP/Getty Images) More From Forbes
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