# year    value 
 1980 -11.56583 
 1981 -11.18547 
 1982 -11.2682 
 1983 -11.6384 
 1984 -11.46785 
 1985 -11.76229 
 1986 -11.25657 
 1987 -11.26753 
 1988 -11.31482 
 1989 -11.26426 
 1990 -11.21592 
 1991 -10.97537 
 1992 -11.27824 
 1993 -11.8432 
 1994 -11.08791 
 1995 -11.39551 
 1996 -11.1417 
 1997 -10.8622 
 1998 -10.48671 
 1999 -11.04114 
 2000 -10.73886 
 2001 -11.0735 
 2002 -11.07562 
 2003 -10.46163 
 2004 -10.95953 
 2005 -10.57301