# year    value 
 1980 -0.1890031 
 1981 -0.1681406 
 1982 -0.3677922 
 1983 -0.4590566 
 1984 -0.3158014 
 1985 -0.2843809 
 1986 -0.2610683 
 1987 -0.1795381 
 1988 -0.100799 
 1989 -0.06778826 
 1990 -0.02542231 
 1991 -0.1226023 
 1992 -0.4580822 
 1993 -0.2795064 
 1994 -0.2100029 
 1995 -0.107416 
 1996 -0.001503574 
 1997 0.06919787 
 1998 0.1070491 
 1999 0.1209353 
 2000 0.1624775 
 2001 0.228432 
 2002 0.2818628 
 2003 0.2521245 
 2004 0.2450613 
 2005 0.8637112