Year Years 1960 1.33 1961 1.268 1962 1.572 1963 1.134 1964 1.507 1965 1.646 1966 1.789 1967 1.899 1968 1.991 1969 1.97 1970 2.193 1971 2.187 1972 1.783 1973 1.999 1974 1.76 1975 1.805 1976 1.784 1977 1.738 1978 2.017 1979 1.499 1980 0.7645 1981 0.2161 1982 -0.4704 1983 -0.8494 1984 -0.8248 1985 -1.027 1986 -1.431 1987 -1.593 1988 -1.934 1989 -1.574 1990 -0.713 1991 -0.03119 1992 0.7102 1993 1.308 1994 1.52 1995 1.809 1996 2.03 1997 2.167 1998 2.247 1999 2.552 2000 2.442 2001 2.347 2002 1.976 2003 1.458