# year value 1960 -0.3894008 1961 -0.4217923 1962 -0.430857 1963 -0.5301753 1964 -0.6728062 1965 -0.6159068 1966 -0.5824358 1967 -0.5466961 1968 -0.554983 1969 -0.555652 1970 -0.5026105 1971 -0.4034672 1972 -0.3880007 1973 -0.3581372 1974 -0.4028178 1975 -0.3946904 1976 -0.3475132 1977 -0.3623679 1978 -0.3184031 1979 -0.2803662 1980 -0.1944333 1981 -0.1772186 1982 -0.3370103 1983 -0.4316775 1984 -0.3097291 1985 -0.2690662 1986 -0.2494248 1987 -0.1729936 1988 -0.09126609 1989 -0.06482648 1990 -0.02663564 1991 -0.1299759 1992 -0.4179983 1993 -0.2619313 1994 -0.2050479 1995 -0.1193371 1996 -0.015659 1997 0.05533013 1998 0.09016552 1999 0.1250977 2000 0.1464488 2001 0.2322673 2002 0.2766429 2003 0.2452436 2004 0.2543302 2005 0.7225893