# year    value 
 1980 -0.443355 
 1981 -0.3973059 
 1982 -0.4733403 
 1983 -0.7177856 
 1984 -0.5281187 
 1985 -0.5365958 
 1986 -0.5250622 
 1987 -0.4234334 
 1988 -0.3314447 
 1989 -0.2767532 
 1990 -0.2129351 
 1991 -0.2201548 
 1992 -0.6151368 
 1993 -0.4884369 
 1994 -0.3828996 
 1995 -0.3650369 
 1996 -0.2522586 
 1997 -0.1559703 
 1998 -0.1016147 
 1999 -0.08117893 
 2000 -0.01553659 
 2001 0.07788412 
 2002 0.08263942 
 2003 0.06350753 
 2004 0.08878138 
 2005 0.1703429