Question: In what race was a Clay County, Kansas native world leader in 1970?

full_context: Document 1: Ken Swenson: Kenneth Lloyd "Ken" Swenson (born April 18, 1948 in Clay Center, Kansas) is a retired middle-distance runner from the United States. Swenson was the world leader at 800 meters in 1970 and competed in the 1972 Summer Olympics in Munich.
Document 2: Clay County, Iowa: Clay County is a county located in the U.S. state of Iowa. As of the 2010 census, the population was 16,667. Its county seat is Spencer. Its name is in honor of Henry Clay, Jr., a colonel who died in action in the Mexican-American War, and son of Henry Clay, famous American statesman.
Document 3: Clay County, Kentucky: Clay County is a county located in the U.S. state of Kentucky. As of the 2010 census, the population was 21,730. Its county seat is Manchester. The county was formed in 1807 and named in honor of Green Clay (1757–1826). Clay was a member of the Virginia and Kentucky State legislatures, first cousin once removed of Henry Clay, U.S. Senator from Kentucky and Secretary of State in the 19th century.
Document 4: James Munyala: James Munyala (born November 2, 1952) is a Kenyan athlete, known for running the steeplechase. Running for the University of Texas, El Paso he won three straight NCAA Championships 1975-1977. His 1976 win set the Franklin Field record that stood for 32 years. He was part of the controversial beginning wave of imported, older Kenyan athletes who allowed UTEP and Washington State University to dominate NCAA distance running. At the time, Craig Virgin suggested these athletes displaced opportunities for American athletes. Another star athlete mentioned was Washington State's Henry Rono who succeeded Munyala as NCAA Champion, with Munyala as runner-up, in 1978, blocking his attempt to win four straight. Later in 1978, Rono and Munyala went 1-2 for Kenya at both the African Games and the Commonwealth Games. Munyala won the Indoor Mile for UTEP in 1978 and is in the university's Hall of Fame when they ran the triple crown of the Men's Indoor, Outdoor and Cross Country Championships all in the same year.
Document 5: Clay Center, Kansas: Clay Center is a city in and the county seat of Clay County, Kansas, United States. As of the 2010 census, the city population was 4,334.
Document 6: Clay County, Missouri: Clay County is a county located in the U.S. state of Missouri. As of the 2010 census, the county had a population of 221,939, making it the fifth-most populous county in Missouri. Its county seat is Liberty. The county was organized January 2, 1822, and named in honor of U.S. Representative Henry Clay from Kentucky, later member of the United States Senate and United States Secretary of State.
Document 7: Jim Ryun: James Ronald Ryun (born April 29, 1947) is a former American politician and track and field athlete. He won a silver medal in the men's 1500 metres at the 1968 Summer Olympics, and was the first high school athlete to run a mile in under four minutes. He is the most recent American to hold the world record for the mile run. Ryun later served in the United States House of Representatives from 1996 to 2007, representing Kansas's 2nd congressional district for the Republican Party.
Document 8: Clay County, Tennessee: Clay County is a county located in the U.S. state of Tennessee. As of the 2010 census, the population was 7,861. Its county seat and only incorporated city is Celina. Clay County is named in honor of American statesman Henry Clay, member of the United States Senate from Kentucky and United States Secretary of State in the 19th century. Its current mayor is Dale Reagan.
Document 9: Steve Scott (athlete): Steve Scott (born May 5, 1956 in Upland, California) is an American male track and field athlete and one of the greatest mile runners in American history. The silver medalist in the 1500 meters at the inaugural IAAF World Championships in Athletics in Helsinki in 1983, Scott owns the U.S. indoor record in the 2000 meters (4:58.6-1981). He held the American outdoor mile record for more than 26 years and also is the former American indoor record holder in the same event. "Track & Field News" ranked Scott #1 in the U.S. on 10 occasions, and 11 times during his career he was ranked in the top ten in the world by T&FN. Additionally, he participated for the US team at the 1984 Summer Olympics. He ran the sub-4:00 minute mile on 136 occasions in his career, more than any other runner in history.
Document 10: Clay County, South Dakota: Clay County is a county located in the U.S. state of South Dakota. As of the 2010 census, the population was 13,864. The county seat is Vermillion, which is also home to the University of South Dakota. The county is named in honor of Henry Clay, American statesman, member of the United States Senate from Kentucky and United States Secretary of State in the 19th century.
Document 11: Ken Martin: Ken Martin (born September 10, 1958) is a former American long-distance runner who is a two-time United States national champion in the marathon. At the 1984 California International Marathon, Martin set a course record with a time of 2:11:24. At the 1985 Pittsburgh Marathon, he competed alongside his wife at the time, Lisa Martin; they became the fastest married couple ever in a marathon and won both of their divisions. He came second in the 1989 New York City Marathon in 2:09:38 to Tanzania’s Juma Ikangaa’s 2:08:01; as of 2007, that was the fourth-fastest marathon time by an American-born athlete.
Document 12: Sebastian Coe: Sebastian Newbold Coe, Baron Coe, {'1': ", '2': ", '3': ", '4': "} (born 29 September 1956), often referred to as Seb Coe or Lord Coe, is a British politician and former track and field athlete. As a middle-distance runner, Coe won four Olympic medals, including the 1500 metres gold medal at the Olympic Games in 1980 and 1984. He set eight outdoor and three indoor world records in middle-distance track events – including, in 1979, setting three world records in the space of 41 days – and the world record he set in the 800 metres in 1981 remained unbroken until 1997. Coe's rivalries with fellow Britons Steve Ovett and Steve Cram dominated middle-distance racing for much of the 1980s.
Document 13: Lincoln Center, Kansas: Lincoln Center, more commonly known as Lincoln, is a city in and the county seat of Lincoln County, Kansas, United States. As of the 2010 census, the city population was 1,297.
Document 14: Steve Prefontaine: Steve Roland "Pre" Prefontaine (January 25, 1951 – May 30, 1975) was an American middle and long-distance runner who competed in the 1972 Olympics. Prefontaine once held the American record in seven different distance track events from the 2,000 meters to the 10,000 meters. Prefontaine died in May 1975 at the age of 24 in an automobile accident in Eugene, Oregon.
Document 15: Clay County, West Virginia: Clay County is a county in the U.S. state of West Virginia. As of the 2010 census, the population was 9,386. Its county seat is Clay. The county was founded in 1858 and named in honor of Henry Clay, famous American statesman, member of the United States Senate from Kentucky and United States Secretary of State in the 19th century.
ground_truth: 800 meters