# year    value 
 1980 -0.1167074 
 1981 -0.1841463 
 1982 -0.2776469 
 1983 -0.3835494 
 1984 -0.2614683 
 1985 -0.3379216 
 1986 -0.2555288 
 1987 -0.1060048 
 1988 -0.08258982 
 1989 -0.0696599 
 1990 0.0101571 
 1991 -0.1635201 
 1992 -0.362826 
 1993 -0.2312158 
 1994 -0.2468229 
 1995 -0.1870103 
 1996 0.03522022 
 1997 0.04442445 
 1998 0.1042288 
 1999 0.1342206 
 2000 0.1287871 
 2001 0.2540629 
 2002 0.3094581 
 2003 0.1678566 
 2004 0.2187846 
 2005 0.1338335