# year value 1960 -0.4915182 1961 -0.5887035 1962 -0.5807918 1963 -0.7314522 1964 -0.8151348 1965 -0.8040026 1966 -0.7021796 1967 -0.6951958 1968 -0.6920054 1969 -0.7339634 1970 -0.5829452 1971 -0.7267494 1972 -0.561692 1973 -0.6433515 1974 -0.5821909 1975 -0.5058648 1976 -0.5848713 1977 -0.4663185 1978 -0.3893605 1979 -0.3704122 1980 -0.4736201 1981 -0.2406619 1982 -0.3809293 1983 -0.6306444 1984 -0.518469 1985 -0.4577459 1986 -0.2941672 1987 -0.2884573 1988 -0.1718148 1989 -0.05465601 1990 0.004073001 1991 -0.2944029 1992 -0.4009577 1993 -0.4905751 1994 -0.2178375 1995 -0.03212382 1996 -0.06812243 1997 0.09777983 1998 0.05389456 1999 0.1140064 2000 0.2949607 2001 0.357353 2002 0.2646391 2003 0.4638568 2004 0.3370336 2005 0.9365567