# year    value 
 1980 -11.07968 
 1981 -10.66819 
 1982 -10.81965 
 1983 -11.04681 
 1984 -10.99729 
 1985 -11.30136 
 1986 -10.71307 
 1987 -10.84149 
 1988 -10.75176 
 1989 -10.77873 
 1990 -10.73181 
 1991 -10.55098 
 1992 -10.77765 
 1993 -11.42416 
 1994 -10.61521 
 1995 -11.09752 
 1996 -10.61204 
 1997 -10.34125 
 1998 -9.996982 
 1999 -10.68194 
 2000 -10.38172 
 2001 -10.53057 
 2002 -10.63726 
 2003 -10.00258 
 2004 -10.45342 
 2005 -10.03896