# year    value 
 1980 -11.60681 
 1981 -11.39583 
 1982 -11.4597 
 1983 -12.07756 
 1984 -11.57345 
 1985 -11.71647 
 1986 -11.58752 
 1987 -11.47893 
 1988 -11.40348 
 1989 -11.51709 
 1990 -11.2692 
 1991 -11.2044 
 1992 -11.81469 
 1993 -11.6814 
 1994 -11.7476 
 1995 -11.26439 
 1996 -11.15126 
 1997 -11.32294 
 1998 -11.34625 
 1999 -11.31763 
 2000  -10.925 
 2001 -11.00771 
 2002 -10.95279 
 2003 -10.87748 
 2004 -10.93008 
 2005 -10.97526