Year | Value | 2021 | 811 | 2020 | 561 | 2019 | 2,270 | 2018 | 2,224 | 2000 | 2,586 | 1999 | 2,500 | 1998 | 2,000 | 1997 | 2,000 | 1996 | 2,700 | 1995 | 2,700 | 1994 | 1,800 | 1993 | 1,600 | 1992 | 1,900 | 1991 | 1,500 | 1990 | 1,400 | 1989 | 1,300 | 1988 | 1,400 | 1987 | 1,800 | 1986 | 1,900 | 1985 | 1,600 | 1984 | 1,500 | 1983 | 1,300 | 1982 | 1,000 | 1981 | 1,300 | 1980 | 600 | 1979 | 500 | 1978 | 700 | 1977 | 700 | 1976 | 600 | 1975 | 600 | 1974 | 600 | 1973 | 600 |
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