| Year | Value | | 2021 | 13,338 | | 2020 | 10,647 | | 2019 | 52,744 | | 2018 | 51,633 | | 2000 | 89,791 | | 1999 | 83,000 | | 1998 | 40,500 | | 1997 | 40,700 | | 1996 | 54,300 | | 1995 | 49,300 | | 1994 | 64,800 | | 1993 | 58,400 | | 1992 | 57,200 | | 1991 | 59,300 | | 1990 | 52,900 | | 1989 | 50,700 | | 1988 | 47,000 | | 1987 | 45,700 | | 1986 | 45,000 | | 1985 | 39,400 | | 1984 | 34,300 | | 1983 | 29,000 | | 1982 | 24,400 | | 1981 | 28,800 | | 1980 | 31,000 | | 1979 | 30,000 | | 1978 | 15,500 | | 1977 | 15,000 | | 1976 | 14,000 | | 1975 | 14,000 | | 1974 | 14,000 | | 1973 | 14,000 |
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