| Year | Value | | 1992 | 1,218 | | 1991 | 9,663 | | 1990 | 27,553 | | 1989 | 51,517 | | 1988 | 95,163 | | 1987 | 175,228 | | 1986 | 317,775 | | 1985 | 386,299 | | 1984 | 396,584 | | 1983 | 407,510 | | 1982 | 416,422 | | 1981 | 425,350 | | 1980 | 431,477 | | 1979 | 436,525 | | 1978 | 429,363 | | 1977 | 437,973 | | 1976 | 448,321 | | 1975 | 459,768 | | 1974 | 468,381 | | 1973 | 471,072 | | 1972 | 475,286 | | 1971 | 483,858 | | 1970 | 485,809 | | 1969 | 483,915 | | 1968 | 485,985 | | 1967 | 485,528 | | 1966 | 483,067 | | 1965 | 488,523 | | 1964 | 485,492 | | 1963 | 483,476 | | 1962 | 476,544 | | 1961 | 465,932 | | 1960 | 460,971 |
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