Williams has won 14 Grand Slam doubles titles, all with her sister Venus, and the pair are unbeaten in Grand Slam doubles finals. As a team, she and Venus have the third most women's doubles Grand Slam titles, behind the 18 titles of Natasha Zvereva (14 with Gigi Fernández) and the record 20 titles won by Martina Navratilova and Pam Shriver. Williams is also a five-time winner of the WTA Tour Championships in the singles division. She has also won four Olympic gold medals, one in women's singles and three in women's doubles—an all-time record shared with her sister, Venus. The arrival of the Williams sisters has been credited with ushering in a new era of power and athleticism on the women's professional tennis tour. Earning almost $29 million in prize money and endorsements, Williams was the highest paid female athlete in 2016. She repeated this feat in 2017 when she was the only woman on Forbes' list of the 100 highest paid athletes with $27 million in prize money and endorsements. She has won the 'Laureus Sportswoman of the Year' award four times (2003, 2010, 2016, 2018), and in December 2015, she was named Sportsperson of the Year by Sports Illustrated magazine.