Year Number 1961 66625 1962 71621 1963 74788 1964 78062 1965 82270 1966 88788 1967 96838 1968 103395 1969 113966 1970 122920 1971 125096 1972 137061 1973 136367 1974 143135 1975 150767 1976 169340 1977 187420 1978 200084 1979 216787 1980 232451 1981 250966 1982 266372 1983 288020 1984 308904 1985 315631 1986 342889 1987 370840 1988 393123 1989 422357 1990 449684 1991 459591 1992 539058 1993 531877 1994 526529 1995 582911 1996 593834 1997 614290 1998 614489