# year    value 
 1980 -0.1542254 
 1981 -0.1656561 
 1982 -0.2951463 
 1983 -0.3930335 
 1984 -0.2644926 
 1985 -0.2605593 
 1986 -0.2539892 
 1987 -0.1649092 
 1988 -0.05583301 
 1989 -0.06221392 
 1990 0.01598644 
 1991 -0.1427823 
 1992 -0.3579248 
 1993 -0.221884 
 1994 -0.2097573 
 1995 -0.1580961 
 1996 -4.094094e-05 
 1997 0.05021625 
 1998 0.09145526 
 1999 0.1046738 
 2000 0.126177 
 2001 0.225945 
 2002 0.2947931 
 2003 0.2019183 
 2004 0.2271626 
 2005 0.147212