| Year | Value | | 2021 | 2,865.737 | | 2020 | 4,635.714 | | 2019 | 7,334 | | 2018 | 10,454 | | 2017 | 24,207 | | 2016 | 22,770 | | 2015 | 23,532 | | 2014 | 25,920 | | 2013 | 21,696 | | 2012 | 17,775 | | 2011 | 25,021 | | 2010 | 21,677 | | 2000 | 3,409 | | 1999 | 3,400 | | 1998 | 1,900 | | 1997 | 4,600 | | 1996 | 7,500 | | 1995 | 7,300 | | 1994 | 7,000 | | 1993 | 5,100 | | 1992 | 5,300 | | 1991 | 5,300 | | 1990 | 5,300 | | 1989 | 5,200 | | 1988 | 5,900 | | 1987 | 6,000 | | 1986 | 5,800 | | 1985 | 6,400 | | 1984 | 6,200 | | 1983 | 5,700 | | 1982 | 5,400 | | 1981 | 4,200 | | 1980 | 4,200 | | 1979 | 4,900 | | 1978 | 4,800 | | 1977 | 4,900 | | 1976 | 4,500 | | 1975 | 4,700 | | 1974 | 4,300 | | 1973 | 3,700 | | 1972 | 4,800 | | 1971 | 4,700 | | 1970 | 4,000 |
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