Question: What year was Sara Alstrom's sister born?

full_context: Document 1: Carolina Gynning: Carolina Gynning Nilsson (born 6 October 1978) is a Swedish glamour model, actress, author, jewelry designer and television presenter. She started her career as a model at age sixteen. She entered the "Big Brother" house in 2004 and emerged as the winner of that season. Gynning has since made a career as a television presenter on TV4 and Kanal5, and also as an artist and author of several books. Gynning has participated in several television shows after "Big Brother" such as "I huvudet på Gynning", and as a celebrity dancer in season one of "Let's Dance".
Document 2: Ewa Aulin: Ewa Brigitta Aulin (born 13 February 1950 in Landskrona, Skåne County) is a former Swedish actress who appeared in a number of Italian and some American films in the 1960s and 1970s. She is remembered for playing the title character in the cult film "Candy" where she appeared alongside such stars as John Huston, Ringo Starr, Walter Matthau, James Coburn, Richard Burton and Marlon Brando. She is known to horror film fans for 3 genre films she starred in..."Death Smiles at a Murderer", "Death Laid an Egg" and "Ceremonia Sangrienta" (aka "Legend of Blood Castle").
Document 3: Arvida Byström: Arvida Byström is a Swedish artist born in 1991 near Stockholm, who is mainly known as a photographer and model but who also makes music. She is based in Los Angeles, London and Stockholm. She cooperates with many magazines and brands such as Nasty Gal, Monki, "Wonderland Magazine", "Lula Magazine", "Vice", "Rookie mag", "Garage magazine", "Baby Baby Baby magazine" and "I heart magazine".
Document 4: Greta Garbo: Greta Garbo (born Greta Lovisa Gustafsson; ] ; 18 September 1905 – 15 April 1990), was a Swedish-born American film actress during the 1920s and 1930s. Garbo was nominated three times for the Academy Award for Best Actress and received an Academy Honorary Award in 1954 for her "luminous and unforgettable screen performances." In 1999, the American Film Institute ranked Garbo fifth on their list of the greatest female stars of classic Hollywood cinema, after Katharine Hepburn, Bette Davis, Audrey Hepburn, and Ingrid Bergman.
Document 5: Hanna Alström: Hanna Carolina Alström (born July 7, 1981) is a Swedish actress.
Document 6: Sara Alström: Sara Catharina Alström (born October 28, 1975 in Stockholm) is a Swedish actress. She started acting when she was 11 years old, then together with her younger sister Hanna. She studied at Balettakademien 1993–95 and Kulturama 1994–96 and later in New York City at Actors Studio and Stella Adler Studio of Acting.
Document 7: Börje Ahlstedt: Nils Börje Ahlstedt (born 21 February 1939) is a Swedish actor who has worked extensively with the world-famous director Ingmar Bergman in films like "Fanny and Alexander" (1982), "The Best Intentions" (1992), "Sunday's Children" (1992) and "Saraband" (2003). Ahlstedt has also worked with the directors Bo Widerberg and Kay Pollak.
Document 8: Hanna Haarala: Hanna Haarala (born in Finland) is a professional Latin American dancer. She has represented Finland with Mikko Kaasalainen at the European and World Games. Her current professional partner is Andrew Cuerden. She competed in series 3 of the BBC's successful dance show Strictly Come Dancing in 2005, reaching seventh place with actor Will Thorp.
Document 9: Hanna in Society: Hanna in Society (Swedish: Hanna i societén) is a 1940 Swedish comedy film directed by Gunnar Olsson and starring Rut Holm, Carl Barcklind and Elsa Carlsson.
Document 10: Lena Olin: Lena Maria Jonna Olin (born 22 March 1955) is a Swedish actress. She has been nominated for several acting awards, including a Golden Globe for "The Unbearable Lightness of Being" (1988) and an Academy Award for "Enemies, A Love Story" (1989). Other well-known films in which she has appeared include "Chocolat" (2000), directed by her husband Lasse Hallström, "Queen of the Damned" (2002), "Casanova" (2005) and "The Reader" (2008). She was cast as Triggerfish's Khumba. Olin was also a main cast member in the second season (and a recurring guest star in later seasons) of the television series "Alias". Olin starred in the Swedish sitcom "Welcome to Sweden".
Document 11: Lena T. Hansson: Lena Teresia Hansson (born 18 May 1955) is a Swedish actress. She studied at Swedish National Academy of Mime and Acting in Stockholm. Hansson is in a relationship with fellow Swedish actor Peter Haber. At the 24th Guldbagge Awards she won the award for Best Actress for her role in "Lethal Film".
Document 12: Hannah Graaf: Hannah Rakel Serafia Graaf Karyd (born "Graf" 31 August 1978 in Gothenburg) is a Swedish glamour model and singer. Graaf along with her model sister, Magdalena, formed a musical duo called The Graaf Sisters.
Document 13: Sara Mearns: Sara Ann Mearns (born 19 January 1986) is an American ballerina who is a principal dancer with New York City Ballet. She was born in Columbia, South Carolina, where she began dance training at the age of three. As a teenager Mearns continued her studies with Patricia McBride and Stanislav Issaev, before entering the School of American Ballet in 2001. She joined the New York City Ballet as an apprentice in 2003, and became a member of the corps de ballet in 2004. She made her debut in a leading role just 18 months later in the dual roles of Odette/Odile in "Swan Lake" at the age of 19. Mearns was promoted to soloist in 2006 and to principal in 2008.
Document 14: Hanna Karjalainen: Hanna Maria Karjalainen (born 8 July 1980 in Oulu) became known in 2003 when she won the "Haluatko filmitähdeksi" ("Do You Want To Be A Film Star?") competition, where the prize was the central role in the film "Levottomat 3". Karjalainen acted in the 2004 movie, but the role was more minor than promised. Before that, Karjalainen had acted in a minor role in the 2001 film "Rölli ja metsänhenki".
Document 15: Stella Kunkat: Kunkat attended a Montessori school in Berlin-Mitte. She sang in the children's choir of the Komische Oper Berlin where she was discovered in 2005 when she took part in the play "Madame Butterfly". At the age of eight, she played her first role in the film "March of Millions" as the daughter of the protagonist who was played by Maria Furtwängler. In 2009, she had the role of the young Romy Schneider in the TV film "Romy". Two years later, Kunkat played the young Sabine Kuegler in "Jungle Child". For that role, she was nominated as Leading Young Performer in an international feature film at the 33rd Young Artist Awards. In the German production "Das Tagebuch der Anne Frank", a film about the Holocaust victim Anne Frank, who wrote the famous diary, Kunkat plays Anne's older sister Margot Frank.
ground_truth: 1981