Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Record | Athlete | Nation | Venue | Date |
| --- | --- | --- | --- | --- |
| 4.02 m | Marc Wright | United States | Cambridge , U.S. | June 8, 1912 |
| 4.09 m | Frank Foss | United States | Antwerp , Belgium | August 20, 1920 |
| 4.12 m | Charles Hoff | Norway | Copenhagen , Denmark | September 22, 1922 |
| 4.21 m | Charles Hoff | Norway | Copenhagen , Denmark | July 22, 1923 |
| 4.23 m | Charles Hoff | Norway | Oslo , Norway | August 13, 1925 |
| 4.25 m | Charles Hoff | Norway | Turku , Finland | September 27, 1925 |
| 4.27 m | Sabin Carr | United States | Philadelphia , U.S. | May 27, 1927 |
| 4.30 m | Lee Barnes | United States | Fresno , U.S. | April 28, 1928 |
| 4.37 m | William Graber | United States | Palo Alto , U.S. | July 16, 1932 |
| 4.39 m | Keith Brown | United States | Boston , U.S. | June 1, 1935 |
| 4.43 m | George Varoff | United States | Princeton, New Jersey , U.S. | July 4, 1936 |
| 4.54 m | Bill Sefton | United States | Los Angeles , U.S. | May 29, 1937 |
| 4.54 m | Earle Meadows | United States | Los Angeles , U.S. | May 29, 1937 |
| 4.60 m | Cornelius Warmerdam | United States | Fresno , U.S. | June 29, 1940 |
| 4.72 m | Cornelius Warmerdam | United States | Compton , U.S. | June 26, 1941 |
| 4.77 m | Cornelius Warmerdam | United States | Modesto , U.S. | May 23, 1942 |
| 4.78 m | Robert Gutowski | United States | Palo Alto , U.S. | April 27, 1957 |
| 4.80 m | Don Bragg | United States | Palo Alto , U.S. | July 2, 1960 |
| 4.83 m | George Davies | United States | Boulder , U.S. | May 20, 1961 |
| 4.89 m | John Uelses | United States | Santa Barbara , U.S. | March 31, 1962 |
| 4.93 m | Dave Tork | United States | Walnut , U.S. | April 28, 1962 |
| 4.94 m | Pentti Nikula | Finland | Kauhava , Finland | June 22, 1962 |
| 5.00 m | Brian Sternberg | United States | Philadelphia , U.S. | April 27, 1963 |
| 5.08 m | Brian Sternberg | United States | Compton | June 7, 1963 |
| 5.13 m | John Pennel | United States | London , England | August 5, 1963 |
| 5.20 m | John Pennel | United States | Coral Gables , U.S. | August 24, 1963 |
| 5.23 m | Fred Hansen | United States | San Diego , U.S. | June 13, 1964 |
| 5.28 m | Fred Hansen | United States | Los Angeles , U.S. | July 25, 1964 |
| 5.32 m | Bob Seagren | United States | Fresno , U.S. | May 14, 1966 |
| 5.34 m | John Pennel | United States | Los Angeles , U.S. | July 23, 1966 |
| 5.36 m | Bob Seagren | United States | San Diego , U.S. | June 10, 1967 |
| 5.38 m | Paul Wilson | United States | Bakersfield , U.S. | June 23, 1967 |
| 5.41 m | Bob Seagren | United States | Lake Tahoe , U.S. | September 12, 1968 |
| 5.44 m | John Pennel | United States | Sacramento , U.S. | June 21, 1969 |
| 5.45 m | Wolfgang Nordwig | East Germany | Berlin , Germany | June 17, 1970 |
| 5.46 m | Wolfgang Nordwig | East Germany | Turin , Italy | September 3, 1970 |
| 5.49 m | Christos Papanikolaou | Greece | Athens , Greece | October 24, 1970 |
| 5.51 m | Kjell Isaksson | Sweden | Austin , U.S. | April 8, 1972 |
| 5.54 m | Kjell Isaksson | Sweden | Los Angeles , U.S. | April 15, 1972 |
| 5.55 m | Kjell Isaksson | Sweden | Helsingborg , Sweden | June 12, 1972 |
| 5.63 m | Bob Seagren | United States | Eugene , U.S. | July 2, 1972 |
| 5.65 m | David Roberts | United States | Gainesville , U.S. | March 28, 1975 |
| 5.67 m | Earl Bell | United States | Wichita , U.S. | May 29, 1976 |
| 5.70 m | David Roberts | United States | Eugene , U.S. | June 22, 1976 |
| 5.72 m | Władysław Kozakiewicz | Poland | Milan , Italy | May 11, 1980 |
| 5.75 m | Thierry Vigneron | France | Paris , France | June 1, 1980 |
| 5.75 m | Thierry Vigneron | France | Lille , France | June 29, 1980 |
| 5.77 m | Philippe Houvion | France | Paris , France | July 17, 1980 |
| 5.78 m | Władysław Kozakiewicz | Poland | Moscow , Soviet Union | July 30, 1980 |
| 5.80 m | Thierry Vigneron | France | Mâcon , France | June 20, 1981 |
| 5.81 m | Vladimir Polyakov | Soviet Union | Tbilisi , Georgia | June 26, 1981 |
| 5.82 m | Pierre Quinon | France | Cologne , Germany | August 28, 1983 |
| 5.83 m | Thierry Vigneron | France | Rome , Italy | September 1, 1983 |
| 5.85 m | Sergey Bubka | Soviet Union | Bratislava , Czechoslovakia | May 26, 1984 |
| 5.88 m | Sergey Bubka | Soviet Union | Paris , France | June 2, 1984 |
| 5.90 m | Sergey Bubka | Soviet Union | London , England | July 13, 1984 |
| 5.91 m | Thierry Vigneron | France | Rome , Italy | August 31, 1984 |
| 5.94 m | Sergey Bubka | Soviet Union | Rome , Italy | August 31, 1984 |
| 6.00 m | Sergey Bubka | Soviet Union | Paris , France | July 13, 1985 |
| 6.01 m | Sergey Bubka | Soviet Union | Moscow , Soviet Union | June 8, 1986 |
| 6.03 m | Sergey Bubka | Soviet Union | Prague , Czechoslovakia | June 23, 1987 |
| 6.05 m | Sergey Bubka | Soviet Union | Bratislava , Czechoslovakia | June 9, 1988 |
| 6.06 m | Sergey Bubka | Soviet Union | Nice , France | July 10, 1988 |
| 6.07 m | Sergey Bubka | Soviet Union | Shizuoka , Japan | May 6, 1991 |
| 6.08 m | Sergey Bubka | Soviet Union | Moscow , Soviet Union | June 9, 1991 |
| 6.09 m | Sergey Bubka | Soviet Union | Formia , Italy | July 8, 1991 |
| 6.10 m | Sergey Bubka | Soviet Union | Malmö , Sweden | August 5, 1991 |
| 6.11 m | Sergey Bubka | Ukraine | Dijon , France | June 13, 1992 |
| 6.12 m | Sergey Bubka | Ukraine | Padua , Italy | August 30, 1992 |
| 6.13 m | Sergey Bubka | Ukraine | Tokyo , Japan | September 19, 1992 |
| 6.14 m A | Sergey Bubka | Ukraine | Sestriere , Italy | July 31, 1994 |
Question:
What is the Nation with a Date that is may 6, 1991?
Answer:
Soviet Union