| Year | Value | | 2001 | 1,832 | | 2000 | 19,349 | | 1999 | 21,365 | | 1998 | 23,563 | | 1997 | 25,946 | | 1996 | 28,531 | | 1995 | 31,515 | | 1994 | 32,346 | | 1993 | 32,808 | | 1992 | 32,380 | | 1991 | 26,951 | | 1990 | 33,934 | | 1989 | 45,084 | | 1988 | 43,733 | | 1987 | 42,363 | | 1986 | 40,995 | | 1985 | 39,612 | | 1984 | 44,425 | | 1983 | 51,491 | | 1982 | 59,274 | | 1981 | 68,112 | | 1980 | 77,965 | | 1979 | 85,753 | | 1978 | 93,035 | | 1977 | 100,476 | | 1976 | 108,172 | | 1975 | 116,351 | | 1974 | 117,685 | | 1973 | 117,414 | | 1972 | 117,038 | | 1971 | 116,410 | | 1970 | 115,111 | | 1969 | 114,563 | | 1968 | 113,263 | | 1967 | 111,320 | | 1966 | 109,044 | | 1965 | 106,504 | | 1964 | 100,876 | | 1963 | 94,565 | | 1962 | 88,270 | | 1961 | 82,251 | | 1960 | 76,681 |
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