# year    value 
 1980 -6.575469 
 1981 -6.462042 
 1982 -6.479317 
 1983 -6.80027 
 1984 -6.668444 
 1985 -6.658237 
 1986 -6.589413 
 1987 -6.474824 
 1988 -6.395586 
 1989 -6.42779 
 1990 -6.272882 
 1991 -6.257852 
 1992 -6.611885 
 1993 -6.557889 
 1994 -6.537889 
 1995 -6.453822 
 1996 -6.287114 
 1997 -6.26931 
 1998 -6.149361 
 1999 -6.217605 
 2000 -6.09384 
 2001 -6.005818 
 2002 -5.926392 
 2003 -5.831306 
 2004 -5.89214 
 2005 -5.810888