| Year | Value | | 2021 | 6,285.619 | | 2020 | 4,377 | | 2019 | 10,215 | | 2018 | 5,817 | | 2017 | 1,087 | | 2016 | 582 | | 2015 | 3,656 | | 2014 | 4,044 | | 2013 | 5,808 | | 2012 | 7,730 | | 2011 | 5,251 | | 2005 | 6,441 | | 2004 | 6,166 | | 2003 | 2,396 | | 2002 | 6,471 | | 2001 | 2,606 | | 2000 | 2,415 | | 1999 | 2,400 | | 1998 | 3,600 | | 1997 | 4,800 | | 1996 | 4,700 | | 1995 | 4,500 | | 1994 | 4,300 | | 1993 | 4,300 | | 1992 | 4,100 | | 1991 | 4,200 | | 1990 | 3,500 | | 1989 | 3,800 | | 1988 | 3,800 | | 1987 | 3,700 | | 1986 | 3,800 | | 1985 | 6,200 | | 1984 | 6,100 | | 1983 | 6,000 | | 1982 | 5,800 | | 1981 | 5,600 | | 1980 | 5,800 | | 1979 | 4,500 | | 1978 | 4,500 | | 1977 | 4,400 | | 1976 | 4,500 | | 1975 | 4,200 | | 1974 | 4,100 | | 1973 | 4,100 | | 1972 | 4,000 | | 1971 | 4,200 | | 1970 | 4,100 |
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