Question: Walter Leslie Duncan, director of the Adelaide Steamship Company, resigned from the Senate in what year?

full_context: Document 1: Stephen Dunham (politician): Stephen Dunham (born 1956) is a former Australian politician. He was the Country Liberal Party member for Drysdale in the Northern Territory Legislative Assembly from 1997 to 2005.
Document 2: Charles McHugh: Charles Stephen McHugh (23 April 1887 – 24 July 1927) was an Australian politician. Born in South Australia, he was educated at Catholic schools before becoming a clerk and an official with the Australian Workers' Union. He served on Thebarton Town Council before being elected to the Australian Senate in 1922 as a Labor Senator for South Australia. He held the seat until his death in 1927; Nationalist John Verran was appointed as his replacement.
Document 3: Walter Leslie Duncan: Walter Leslie Duncan (14 February 1883 – 28 May 1947) was an Australian politician. Born in Armidale, New South Wales, he was educated at state schools before becoming a clerk, and was President of the Labor Council of New South Wales in 1911. A member of the Labor Party, he joined the Nationalists in the wake of the 1916 split over conscription. Duncan enlisted in the military in 1917, leaving in 1919 to successfully contest the Senate for the Nationalists. A strong supporter of Billy Hughes, he was excluded from the party along with Hughes in 1929 and joined the Australian Party, before being reaccepted into the United Australia Party in 1931. He resigned from the Senate in 1931. He was also a Director of the Adelaide Steamship Company for many years. Duncan died in 1947.
Document 4: Pacific Steamship Company: The Pacific Steamship Company was an American freight and passenger shipping company that operated between 1916 and 1936. The company was formed by the merger of the Pacific Coast Steamship Company and the Pacific-Alaska Navigation Company and was a direct competitor to the Alaska Steamship Company in the Alaska-Seattle shipping business.
Document 5: James Guthrie (Australian politician): James Francis Guthrie (13 September 1872 – 18 August 1958) was an Australian politician. Born at Rich Avon Station in Victoria, he was educated at Geelong College before becoming a grazier, sheep breeder and woolbroker. In 1919, he was elected to the Australian Senate as a Nationalist Senator for Victoria. In 1931, together with the rest of his party, he joined the United Australia Party. He held the seat until his defeat in 1937, taking effect in 1938. Guthrie died in 1958.
Document 6: George Henderson (Australian politician): Christopher George Henderson (19 August 1857 – 21 January 1933) was a Scottish-born Australian politician. Born in Clackmannanshire, he received a primary education before migrating to Australia in 1885. He was a coal miner in New South Wales and general secretary of the Illawarra Miners' Union. He moved to Western Australia around 1900, becoming a coal miner at Collie and serving on Collie Municipal Council. In 1903, he was elected to the Australian Senate as a Labor Senator for Western Australia. He served as Chairman of Committees from 1914 to 1917. Henderson left the Labor Party in the wake of the 1916 split over conscription, joining the new Nationalist Party. He remained a Nationalist Senator until his defeat in 1922. Henderson died in 1933.
Document 7: Union Steamship Company of British Columbia: The Union Steamship Company of British Columbia was a pioneer firm on coastal British Columbia. It was founded in November 1889 by John Darling, a director of the Union Steamship Company of New Zealand, and nine local businessmen. The company began by offering local service on Burrard Inlet near Vancouver and later expanded to servicing the entire British Columbia coast. Initially a cross-harbour service with the steamers "Senator" and "Lonsdale", the line was asked to take on more roles, calling in at Howe Sound, Gibsons Landing, and various logging camps and sawmills. The demand outstripped the availability of vessels.
Document 8: J. Walter Duncan: J. Walter Duncan Jr. (November 26, 1916 – February 21, 2009) was an American businessman. He was born in Illinois, but moved to Oklahoma in 1949. He worked in the oil and gas industry. In 1983, he became owner of the New Jersey Generals, he sold the team to Donald Trump after the 1983 USFL season.
Document 9: Pacific Coast Steamship Company: The Pacific Coast Steamship Company was an important early shipping company that operated steamships on the west coast of North America. Organized in 1867 under the name of Goodall, Nelson and Perkins the company. The Goodall, Nelson & Perkins Steamship Company was formed in 1875, but a year later reorganized as the Pacific Coast Steamship Company. In 1916 the Admiral Line bought the shipping interests of the company.
Document 10: John Spalvins: John Spalvins, born Janis Gunnars Spalvins, in 1936, in Latvia, was Managing Director of the Adelaide Steamship Company from 1977 until the company's collapse in 1991. During this period under Spalvins' control, "AdSteam" became Australia's major corporate entity with interests and significant holdings in retailing, food, wine, dairy, hardware, building, banks, and numerous other companies. "Spalvins built up one of Australia's largest industrial conglomerates, which took in David Jones, Woolworths, Metro Meat, food company Petersville Sleigh, beer and wine company Tooth & Co, as well as a tugboat business, before it was put into receivership in 1991."
Document 11: Alaska Steamship Company: The Alaska Steamship Company was formed on August 3, 1894. While it originally set out to ship passengers and fishing products, the Alaska Steamship Company began shipping mining equipment, dog sleds, and cattle at the outbreak of the Klondike Gold Rush of 1897. The company was purchased by the Alaska Syndicate and merged with the Northwestern Steamship Company in 1909, but retained its name, and the fleet was expanded to 18 ships. During World War II, the government took over the company's ships. When the war ended, the company struggled to compete with the new Alaska Highway for passengers and freight. It discontinued passenger service altogether in 1954 and shut down operations in 1971.
Document 12: Wes Fang: Wesley (Wes) Joseph Fang is an Australian politician. He has been a NSW Nationals member of the New South Wales Legislative Council since 9 August 2017, when he filled a casual vacancy caused by the resignation of Duncan Gay. Fang has Singaporean heritage and is the first Asian-Australian to represent the Nationals in the New South Wales Parliament. Fang holds a degree in aviation from the University of New South Wales and was formerly a pilot with the Australian Army and Telstra Child Flight, a director of the Wagga Wagga Business Chamber and founded the Wagga Ratepayers' Community.
Document 13: Alister McMullin: Sir Alister Maxwell McMullin, {'1': ", '2': ", '3': ", '4': "} (14 July 1900 – 7 August 1984) was an Australian politician. Born in Scone, New South Wales, he was educated at state schools before becoming a farmer and grazier. He served in the Royal Australian Air Force in 1940-1945, and when he returned served on Upper Hunter Shire Council. In 1951, he was elected to the Australian Senate as a Liberal Senator for New South Wales. In 1953, he succeeded Ted Mattner as President of the Senate; he served as President for 18 years, until his retirement from the Senate in 1971. He is thus the longest serving President of the Senate in Australian history.
Document 14: Adelaide Steamship House: The Adelaide Steamship House is located at 10-12 Mouat Street, Fremantle. Built in 1900, the building was designed by Fremantle based architectural firm Charles Oldham and Herbert Eales and was constructed by C. Coghill. The building takes its name from the original owners of the building, the Adelaide Steamship Company, who provided sea passenger and freight services around Australia.
Document 15: Adelaide Steamship Company: The Adelaide Steamship Company was formed by a group of South Australian businessmen in 1875. Their aim was to control the transport of goods between Adelaide and Melbourne and profit from the need for an efficient and comfortable passenger service. For the first 100 years of its life, the main activities of the company were conventional shipping operations on the Australian coast, primary products, consumer cargoes and extensive passenger services.
ground_truth: 1931