Question: The woman Serena Williams defeated at the 2014 US Open – Women's Singles was born in what year?
Context: Serena Williams was the two-time defending champion and successfully defended her title, defeating Caroline Wozniacki in the final, 6–3, 6–3.  Williams did not lose a set in the entire tournament and did not lose more than three games in any set.  This was Williams' 18th Grand Slam singles title, tying the number won by Martina Navratilova and Chris Evert.  With the victory, Serena tied the open era record of six US Open titles held by Evert.  This was Williams' third US Open championship that she competed in without losing a set, also tying Evert. The 2010 Billie Jean King Cup was the 2nd edition of this tennis exhibition tournament.  Seven-time Grand Slam champion Venus Williams, 2009 French Open Champion Svetlana Kuznetsova, and 2009 US Open Champion Kim Clijsters participated.  2009 Australian Open and Wimbledon Champion Serena Williams had to withdraw from the event due to a leg injury.  She was replaced by 2008 French Open Champion Ana Ivanovic.  In the first semifinal, Clijsters defeated Ivanovic in a tiebreaker (7–2), despite Ivanovic having match point at 5–4 up.  Williams defeated Kuznetsova in the second semifinal, 6–4.  Williams defeated Clijsters in the championship match by a score of 6–4 3–6 7–5. In tennis, the 2013 US Open Series (known as Emirates Airline US Open Series for sponsorships reasons) was the tenth edition of the US Open Series, which included ten hard court tournaments that started on July 20, 2013 in Atlanta and concluded in Winston-Salem for the men and in New Haven for the women on August 24, 2013.  This edition consisted of four separate men's tournaments and four women's tournaments, with the Western & Southern Open hosting both a men's and women's event.  The series was headlined by two ATP World Tour Masters 1000 and two WTA Premier 5 events.  Rafael Nadal and Serena Williams were the US Open Series winners, making them eligible for a $1 million bonus if either also won the US Open, a feat which they both accomplished, hence receiving the largest paychecks to date for a single tennis tournament, totalling $3.6 million each. In tennis, the 2014 US Open Series (known as Emirates Airline US Open Series for sponsorship reasons) was the eleventh edition of the US Open Series, which included nine hard court tournaments that started on July 21, 2014 in Atlanta and concluded in Winston-Salem for the men and in New Haven for the women on August 23, 2014.  This edition consisted of four separate men's tournaments and three women's tournaments, with the Western & Southern Open hosting both a men's and women's event.  The series was headlined by two ATP World Tour Masters 1000 and two WTA Premier 5 events.  Milos Raonic and Serena Williams were the US Open Series champions in 2014.  Serena Williams improved the biggest payout in professional tennis history record which she previously shared with Rafael Nadal.  The new record was then set at $4 million. Omar Jasika (; born 18 May 1997) is an Australian tennis player.  He is the 2014 US Open boys' singles champion defeating Quentin Halys in the final.  Jasika along with Naoki Nakagawa also won the 2014 US Open boys' doubles title after defeating Rafael Matos and João Menezes in the final.  In winning both, Jasika became the first player in 28 years to win both the boys’ singles and doubles events at the US Open. Ekaterina Valeryevna Makarova (Russian: Екатери́на Вале́рьевна Мака́рова ; ] ; born on 7 June 1988) is a Russian professional tennis player.  She achieved her career-high ranking of number 8 on 6 April 2015.  Her best Grand Slam singles results have come at the 2014 US Open and the 2015 Australian Open where she reached the semifinals on both occasions.  Makarova is a four-time Grand Slam champion in doubles competition, having won the 2012 US Open mixed doubles tournament with Bruno Soares, and the 2013 French Open, the 2014 US Open and 2017 Wimbledon Championships with Elena Vesnina. Caroline Wozniacki (] , ] ; born 11 July 1990) is a Danish professional tennis player.  She is a former world No. 1 on the WTA Tour, having held this position for 67 weeks.  She was the first woman from a Scandinavian country to hold the top ranking position and 20th overall.  She finished on top of the rankings in both 2010 and 2011. The Williams sisters are two professional American tennis players: Venus Williams (b. 1980), a seven-time Grand Slam title winner (singles), and Serena Williams (b. 1981), twenty-three-time Grand Slam title winner (singles), both of whom were coached from an early age by their parents Richard Williams and Oracene Price.  There is a noted professional rivalry between them – between the 2001 US Open and the 2017 Australian Open tournaments, they met in nine Grand Slam singles finals.  They became the first two players, female or male, to play in 4 consecutive grand slam singles finals from the 2002 French Open to the 2003 Australian Open; Serena famously won all 4 to complete the first of two "Serena Slams".  Between 2000 and 2016, a 17-year span, they collectively won 12 Wimbledon singles titles (Venus won 5 and Serena won 7).  By winning the 2001 Australian Open women's doubles title, they became the 5th pair to complete the Career Doubles Grand Slam and the only pair to complete the Career Doubles Golden Slam.  At the time, Venus and Serena were only 20 and 19 years old, respectively.  Since then they have gone on to add another two Olympic gold medals in the 2008 Beijing Olympics and the 2012 London Olympics.  Nearly a decade later, the duo would go on to win 4 consecutive grand slam doubles titles from 2009 Wimbledon through 2010 Roland Garros, which would catapult them to co-No.  1 doubles players on 7 June 2010.  Two weeks later, on 21 June 2010, Serena would hold the No. 1 singles ranking and Venus would be right behind her at No. 2 in singles.  Their most recent grand slam doubles titles came at the 2012 Wimbledon & 2016 Wimbledon events.  They remain very close, often watching each other's matches in support, even after one of them has been knocked out of a tournament. This is a list of the main career statistics of professional Danish tennis player Caroline Wozniacki.  To date, Wozniacki has won twenty-six WTA singles titles including two WTA Premier Mandatory singles titles and three WTA Premier 5 singles titles.  She was also the runner-up at the 2009 US Open, 2010 WTA Tour Championships, and 2014 US Open, a semi-finalist at the 2010 US Open, 2011 Australian Open and 2011 US Open and a quarterfinalist at the 2010 French Open and 2012 London Olympics.  Wozniacki was first ranked World No. 1 by the Women's Tennis Association (WTA) on October 11, 2010. The 1999 US Open – Women's Singles was the women's singles event of the hundred-and-ninth edition of the US Open, the fourth and last Grand Slam of the year, and the most prestigious tournament in the Americas.  Lindsay Davenport was the defending champion, but she was defeated in the semifinals by Serena Williams.  Williams then won in the final, defeating World No. 1 Martina Hingis.  This was Williams' first Grand Slam title, and she became the first African American woman to win a Grand Slam in the Open Era.  She won five more titles in 2002, 2008, 2012, 2013 and 2014.
Answer: 1990