Question: When was the inventor of the wobble board born?

full_context: Document 1: Rolf de Heer: Rolf de Heer (born 4 May 1951) is a Dutch Australian film director. De Heer was born in Heemskerk in the Netherlands but migrated to Sydney when he was eight years old. He attended the Australian Film, Television and Radio School in Sydney. His company is called Vertigo Productions and is based in Adelaide. De Heer primarily makes alternative or arthouse films. According to the jacket notes of the videotape, de Heer holds the honor of co-producing and directing the only motion picture, "Dingo", in which the jazz legend Miles Davis appears as an actor. Miles Davis collaborated with Michel Legrand on the score. He is the subject of the book "Dutch Tilt, Aussie Auteur: The Films of Rolf de Heer" (First edition – Saarbrücken, Germany: VDM, 2009. Second edition – Ebook: Starrs via Smashwords.com, 2013) by Dr D. Bruno Starrs. A comprehensive study of his films to date, "Dancing to His Song: the Singular Cinema of Rolf de Heer" by film critic Jane Freebury, is published in ebook and print (Currency Press & Currency House, 2015).
Document 2: May Howlett: May Howlett (born 1931) is an Australian composer and actress. She earned a bachelor's degree in music in 1954, from Melbourne University. In 1955 she earned a Diploma of Education. In 1971 she was given her first commission, which was a commission for a cantata for the first concert of the Canberra New Music Society. She was then offered the first composition scholarship at the Canberra School of Music. In 1973 she toured with Young Opera for the Arts Council of New South Wales. Subsequently she appeared in an ABC TV opera production of Malcolm Williamson's "Violins of St. Jacques", and became involved in acting. For approximately the next twenty years she acted, appearing in six films, various television shows and series, and on the stage. She also took her original one-woman show to Carnegie Hall. In 1981 she toured with Barry Humphries as his associate pianist. In 1987 she began composing again, and also became a production coordinator and assistant director with the New South Wales Department of Education. In 1989, she created the State Drama Camp and the State Drama Festival. In 1996 she and Audley Green received an artist-in-residency to complete a work-in-progress for harpsichord, viola and cello. In 2006, she earned a master's degree in music from Macquarie University; her thesis was titled "The Production of a Contemporary Chamber Opera", and was accompanied by a revised score, with piano reduction and workshop recording, of her chamber opera, "The Boy Who Wasn't There."
Document 3: Rove McManus: John Henry Michael McManus (born 21 January 1974), as stage name Rove McManus, is an Australian triple Gold Logie award-winning television presenter, producer, comedian and media personality. He was the host of the comedy talk show "Rove LA" and was also the host of the eponymous variety show "Rove." He is also the co-owner of the production company Roving Enterprises with partner Craig Campbell.
Document 4: The Fabulous Kangaroos: The Fabulous Kangaroos was a professional wrestling tag team that existed in various forms from 1957 until 1983. The first incarnation of The Fabulous Kangaroos was formed when Italian Australian Al Costello teamed with Australia native Roy Heffernan and adopted an "Ultra Australian" gimmick complete with boomerangs, bush hats, and the song "Waltzing Matilda" as their entrance music. Costello and Heffernan are arguably the most famous version of The Kangaroos, regarded as one of the top tag teams to ever compete in professional wrestling, and are often credited with popularizing tag team wrestling in the late 1950s and 1960s.
Document 5: Sun Arise: "Sun Arise" is the fourth single released by the Australian singer-songwriter Rolf Harris. Released in January 1961 in Australia and October 1962 in the UK, it was Harris' third charting hit in Australia (following "The Big Black Hat" in 1960) and second in the UK (following "Tie Me Kangaroo Down, Sport" also 1960). Unlike his early chart hits, "Sun Arise" was not a comedy record, but came within the genre of world music with its didgeridoo-inspired sound.
Document 6: Steve Tibbetts: Tibbetts plays acoustic and electric guitar as well as exotic percussive instruments such as the kendang and kalimba. His musical compositions span several genres and styles including experimental, jazz, rock, ambient, and world music. He has self described his music as "post modern neo-primitivism". Often more than one genre or style is found in a single composition. A variety of techniques may be used with the guitar such as a string-bending technique sonically imitating a sarangi with a 12-string guitar while also alternating between ambient soundscape and Hendrix-like distorted and feedbacked leads with an electric guitar. He incorporates field-recordings such as the footsteps in the track "Running" from "Safe Journey", or the chanting of Nepalese villagers from the last tracks of "Big Map Idea". Tibbetts' recordings often include percussion by St Paul's Marc Anderson.
Document 7: Mark Holden: Mark Ronald Holden (born 27 April 1954) is an Australian singer, actor, TV personality, record producer, songwriter, and barrister. He was a pop star in the 1970s and had four top 20 hit singles, "Never Gonna Fall in Love Again" (May 1976), "I Wanna Make You My Lady" (September), "Last Romance" (November) and "Reach Out for the One Who Loves You" (October 1977). Holden regularly appeared on national pop music show, "Countdown". Holden is remembered for his clean-cut image, his white dinner suit and his penchant for handing out carnations to girls on the set of the popular television show "Countdown" – he was nicknamed "The Carnation Kid". In the 1980s he worked as a songwriter in Los Angeles providing material recorded by Meat Loaf, Joe Cocker, Gladys Knight, Bob Welch and Steve Jones. He was one of three original judges on the TV series "Australian Idol" (2003–07) and the first season (2005) of "The X Factor".
Document 8: Paul Harris (film critic): Paul Harris, born in 1950 in Melbourne and educated at Assumption College, Kilmore is a film critic, who appears on radio stations 3RRR and 3AW. Known for his vast knowledge of film, music and theatre, and for his elaborate puns and impressions, he has fronted the radio show "Filmbuff's Forecast" since 1982. For the first ten years he co-anchored with John Flaus to produce what became a memorable double act. He has directed the St Kilda Short Film Festival since 1999.
Document 9: Bob Harris (radio): Robert Brinley Joseph Harris, OBE (born 11 April 1946), known as "'Whispering Bob Harris", is an English music presenter known for being a host of the BBC2 music programme "The Old Grey Whistle Test", and as a co-founder of the listings magazine "Time Out".
Document 10: Richard Harris: Richard St John Harris (1 October 1930 – 25 October 2002) was an Irish actor and singer. He appeared on stage and in many films, appearing as Frank Machin in "This Sporting Life", for which he was nominated for the Academy Award for Best Actor, King Arthur in the 1967 film "Camelot" and the subsequent 1981 revival of the show. He played an aristocrat and prisoner in "A Man Called Horse" (1970), a gunfighter in Clint Eastwood's Western film "Unforgiven" (1992), Emperor Marcus Aurelius in "Gladiator" (2000), and Albus Dumbledore in the first two "Harry Potter" films: "the Philosopher's Stone" (2001) and "the Chamber of Secrets" (2002). Harris had a number one hit in Australia and Canada and a top ten hit in the United Kingdom and United States with his 1968 recording of Jimmy Webb's song "MacArthur Park".
Document 11: Peter Allen (musician): Peter Allen (born Peter Richard Woolnough; 10 February 1944 – 18 June 1992) was an Australian-born singer-songwriter, musician and entertainer, known for his flamboyant stage persona and lavish costumes. His songs were made popular by many recording artists, including Elkie Brooks, Melissa Manchester and Olivia Newton-John, with one, "Arthur's Theme" by Christopher Cross, winning an Academy Award for Best Original Song in 1981. In addition to recording many albums, he enjoyed a cabaret and concert career, including appearing at the Radio City Music Hall riding a camel. His Australian patriotism song "I Still Call Australia Home", has been used extensively in advertising campaigns, and was added to the National Film and Sound Archive's Sounds of Australia registry in 2013.
Document 12: Rolf Harris: Rolf Harris (born 30 March 1930) is an Australian entertainer whose career has encompassed work as a musician, singer-songwriter, composer, comedian, actor, painter and television personality.
Document 13: Paul Kelly (Australian musician): Paul Maurice Kelly {'1': ", '2': ", '3': ", '4': "} (born 13 January 1955) is an Australian rock music singer-songwriter, guitarist, and harmonica player. He has performed solo, and has led numerous groups, including the Dots, the Coloured Girls, and the Messengers. He has worked with other artists and groups, including associated projects Professor Ratbaggy and Stardust Five. Kelly's music style has ranged from bluegrass to studio-oriented dub reggae, but his core output straddles folk, rock, and country. His lyrics capture the vastness of the culture and landscape of Australia by chronicling life about him for over 30 years. David Fricke from "Rolling Stone" calls Kelly "one of the finest songwriters I have ever heard, Australian or otherwise." Kelly has said, "Song writing is mysterious to me. I still feel like a total beginner. I don't feel like I have got it nailed yet".
Document 14: Wobble board: The wobble board is a musical instrument invented and popularized by the Australian musician and artist Rolf Harris, and is featured in his best-known song "Tie Me Kangaroo Down, Sport". A wobble board, like some other musical instruments, can be ornately decorated because its large surface area can act as a canvas without detracting from its musical capability.
Document 15: Paul Field (musician): Paul Field (born 3 May 1961) is an Australian musician. He is best known as one of the founding members of the Sydney pub rock band The Cockroaches and The Field Brothers and as Managing Director for the children's music group The Wiggles.
ground_truth: (born 30 March 1930