Year Years 1960 4.004 1961 4.884 1962 4.427 1963 4.291 1964 4.026 1965 3.908 1966 3.833 1967 3.52 1968 3.93 1969 3.883 1970 4.062 1971 3.743 1972 4.39 1973 5.041 1974 5.407 1975 5.537 1976 6.233 1977 6.052 1978 5.398 1979 5.483 1980 5.309 1981 4.004 1982 3.137 1983 1.641 1984 1.386 1985 1.742 1986 1.601 1987 1.902 1988 1.602 1989 1.494 1990 0.2441 1991 0.7589 1992 0.6132 1993 1.28 1994 1.426 1995 0.5687 1996 0.05024 1997 -0.2593 1998 -0.163 1999 -0.4434 2000 0.5141 2001 0.4627 2002 0.4183 2003 0.6183