Question: In what year was the oldest partner of the 2015 Russian national champion ice dancers born?
Context: The Denkova-Staviski Cup is an annual international figure skating competition named after two-time World champion ice dancers Albena Denkova / Maxim Staviski of Bulgaria.  It is held in November and December in Sofia, Bulgaria.  In some years the senior event is part of the ISU Challenger Series.  Medals may be awarded in the disciplines of men's singles, ladies' singles, pair skating, and ice dancing. Sergey Alexandrovich Mozgov (Russian: Серге́й Александрович Мозгов ; born 10 March 1995) is a Russian ice dancer.  With former partner Anna Yanovskaya, he is the 2015 World Junior champion, two-time (2013, 2014) JGP Final champion, the 2012 Youth Olympics champion, the 2014 World Junior silver medalist, and the 2015 Russian junior national champion. Ruslan Nailevich Zhiganshin (Russian: Руслан Наильевич Жиганшин ; born 25 September 1992) is a Russian ice dancer.  With partner Elena Ilinykh, he is the 2015 Russian national champion. Kirill Leonidovich Khaliavin (Russian: Кирилл Леонидович Халявин ; born 21 November 1990) is a Russian ice dancer who currently represents Spain.  With former partner Ksenia Monko, he is the 2011 World Junior champion, a two-time (2009–10, 2010–11) Junior Grand Prix Final champion, and the 2015 Russian national silver medalist.  With current partner Sara Hurtado, he is the 2016 Spanish Champion. Alexander Dmitriyevich Petrov (Russian: Александр Дмитриевич Петров ; born 26 April 1999) is a Russian figure skater.  He is the 2016 CS Nebelhorn Trophy champion and the 2016 Russian National bronze medalist.  On the junior level, he is the 2014–15 Junior Grand Prix Final bronze medalist and the 2015 Russian Junior National champion.  Petrov holds the title of Master of Sports of Russia. Danielle O'Brien (born 7 February 1990) is an Australian ice dancer.  With partner Gregory Merriman, she is a six-time Australian senior national champion and three-time junior national champion.  They have competed at the World Championships and Four Continents Championships since 2008, and have competed at three World Junior Championships.  They became the first Australian ice dancers to reach the free dance at a World Championships. Evgenia Armanovna Medvedeva (Russian: Евгения Армановна Медведева ; born 19 November 1999) is a Russian figure skater.  She is a two-time World champion (2016, 2017), a two-time European champion (2016, 2017), a two-time Grand Prix Final champion (2015, 2016), and a two-time Russian national champion (2016, 2017).  Earlier in her career, she won the 2015 World Junior Championships, the 2014 Junior Grand Prix Final, and the 2015 Russian Junior Championships. Elena Ruslanovna Ilinykh (Russian: Еле́на Русла́новна Ильины́х ; born 25 April 1994) is a Russian ice dancer.  With partner Ruslan Zhiganshin, she is the 2015 Russian national champion. Yelena Igorevna Radionova (Russian: Елена Игоревна Радионова ; born 6 January 1999) is a Russian figure skater.  She is the 2015 World bronze medalist, a two-time (2015–2016) European silver medalist, a two-time Grand Prix Final medalist, 2017 Winter Universiade champion and the 2015 Russian national champion.  On the junior level, she won two World Junior titles (2013 & 2014) and the 2012–13 JGP Final. Gregory Merriman (born 3 October 1988) is an Australian ice dancer.  With partner Danielle O'Brien, he is a six-time Australian senior national champion and three-time junior national champion.  They have competed at the World Championships and Four Continents Championships since 2008, and have competed at three World Junior Championships.  They became the first Australian ice dancers to reach the free dance at a World Championships and the second Ice Dance couple from Australia to compete at the Winter Olympics.
Answer: 1992