# year    value 
 1960 -0.310989 
 1961 -0.2943055 
 1962 -0.3438516 
 1963 -0.4169848 
 1964 -0.5378688 
 1965 -0.4712632 
 1966 -0.4259833 
 1967 -0.3470858 
 1968 -0.3619287 
 1969 -0.3618753 
 1970 -0.3459723 
 1971 -0.2745533 
 1972 -0.249233 
 1973 -0.280558 
 1974 -0.2817952 
 1975 -0.2981304 
 1976 -0.2980384 
 1977 -0.2119183 
 1978 -0.2240325 
 1979 -0.1647378 
 1980 -0.1450067 
 1981 -0.1155533 
 1982 -0.2031944 
 1983 -0.2835977 
 1984 -0.1962921 
 1985 -0.1685063 
 1986 -0.1776831 
 1987 -0.1417747 
 1988 -0.1007147 
 1989 -0.04387369 
 1990 -0.03058946 
 1991 -0.07439228 
 1992 -0.281226 
 1993 -0.1967184 
 1994 -0.1145439 
 1995 -0.07388073 
 1996 -0.01253068 
 1997 0.03619914 
 1998 0.07689531 
 1999 0.09066902 
 2000 0.09518114 
 2001 0.1747608 
 2002 0.1985219 
 2003 0.1943449 
 2004 0.148586 
 2005 -0.08249745