# year value 1960 -0.4412663 1961 -0.3807352 1962 -0.4831774 1963 -0.4902666 1964 -0.7526462 1965 -0.7374886 1966 -0.672047 1967 -0.530482 1968 -0.6043387 1969 -0.7734485 1970 -0.6331424 1971 -0.4581751 1972 -0.470833 1973 -0.5309341 1974 -0.535968 1975 -0.5447855 1976 -0.4836896 1977 -0.4613041 1978 -0.3885328 1979 -0.1938164 1980 -0.3260167 1981 -0.2094216 1982 -0.4604367 1983 -0.686646 1984 -0.4454139 1985 -0.4389254 1986 -0.2212953 1987 -0.2791216 1988 -0.2348755 1989 -0.09603365 1990 -0.2101509 1991 -0.04664167 1992 -0.6564461 1993 -0.4783429 1994 0.01214596 1995 -0.1323392 1996 -0.0690964 1997 0.1448651 1998 0.237197 1999 0.06928998 2000 0.4037232 2001 0.1315369 2002 0.2720222 2003 0.3947392 2004 0.3791994 2005 1.328684