| Year | Value | | 2021 | 19,318.46755748 | | 2020 | 17,471.065564645 | | 2019 | 18,587.777079677 | | 2018 | 18,831.445305821 | | 2017 | 17,263.457030158 | | 2016 | 16,058.319567021 | | 2015 | 15,410.878012681 | | 2014 | 17,781.067521939 | | 2013 | 17,588.490925288 | | 2012 | 16,374.40144129 | | 2011 | 18,736.50805268 | | 2010 | 17,942.089396493 | | 2009 | 18,430.258025682 | | 2008 | 19,952.09103 | | 2007 | 18,495.424416895 | | 2006 | 16,057.544247232 | | 2005 | 15,491.624465705 | | 2004 | 14,937.843013577 | | 2003 | 13,119.006820724 | | 2002 | 10,710.617500519 | | 2001 | 9,719.101153848 | | 2000 | 9,581.1709655366 | | 1999 | 10,587.887064197 | | 1998 | 10,359.037516455 | | 1997 | 9,810.4535788466 | | 1996 | 10,379.760806851 | | 1995 | 10,041.034881357 | | 1994 | 8,591.6138696526 | | 1993 | 8,262.7146609379 | | 1992 | 9,395.0928818342 | | 1991 | 7,693.7106485273 | | 1990 | 6,718.2148646538 | | 1989 | 5,100.4479287948 | | 1988 | 4,691.1779333414 | | 1987 | 3,969.6477266008 | | 1986 | 3,148.041715617 | | 1985 | 2,149.0693791978 | | 1984 | 1,986.544120583 | | 1983 | 2,181.5218906739 | | 1982 | 2,443.9347677501 | | 1981 | 2,647.3989478155 | | 1980 | 2,775.5938092967 | | 1979 | 2,272.5835585033 | | 1978 | 2,018.206148501 | | 1977 | 1,911.4470511817 | | 1976 | 1,837.2953612568 | | 1975 | 1,780.0074723807 | | 1974 | 1,708.2596535893 | | 1973 | 1,471.4512084236 | | 1972 | 1,072.6285622511 | | 1971 | 877.46029436428 | | 1970 | 772.14361023383 |
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