| Year | Value | | 2021 | 1,929 | | 2020 | 1,090 | | 2019 | 4,990.79 | | 2018 | 4,976 | | 2017 | 8,439 | | 2016 | 10,604 | | 2015 | 11,462 | | 2014 | 10,380 | | 2013 | 12,132 | | 2012 | 7,011 | | 2011 | 4,817 | | 2010 | 3,755.3336328915 | | 2003 | 4,783 | | 2002 | 4,505 | | 2001 | 5,235 | | 2000 | 6,257 | | 1999 | 6,000 | | 1998 | 10,300 | | 1997 | 10,200 | | 1996 | 5,400 | | 1995 | 6,300 | | 1994 | 4,900 | | 1993 | 4,900 | | 1992 | 4,700 | | 1991 | 4,800 | | 1990 | 4,100 | | 1989 | 4,700 | | 1988 | 4,500 | | 1987 | 4,400 | | 1986 | 6,700 | | 1985 | 6,400 | | 1984 | 6,000 | | 1983 | 6,100 | | 1982 | 5,600 | | 1981 | 5,300 | | 1980 | 4,300 | | 1979 | 4,400 | | 1978 | 4,300 | | 1977 | 4,000 | | 1976 | 4,000 | | 1975 | 3,800 | | 1974 | 3,600 | | 1973 | 3,600 | | 1972 | 3,400 | | 1971 | 3,700 | | 1970 | 3,700 |
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