# year    value 
 1980 -2.577086 
 1981 -2.454636 
 1982 -2.758264 
 1983 -2.829879 
 1984 -2.612897 
 1985 -2.714996 
 1986 -2.727812 
 1987 -2.406419 
 1988 -2.449687 
 1989 -2.447562 
 1990 -2.166356 
 1991 -2.279557 
 1992 -2.297681 
 1993 -2.366648 
 1994 -2.271209 
 1995 -2.405993 
 1996 -2.260756 
 1997 -2.073008 
 1998 -1.997931 
 1999 -1.908158 
 2000 -1.790878 
 2001 -1.597328 
 2002 -1.764798 
 2003 -1.727901 
 2004 -1.756072 
 2005 -1.392938