# year    value 
 1980 -2.457738 
 1981 -2.375418 
 1982 -2.652431 
 1983 -2.711035 
 1984 -2.497299 
 1985 -2.61686 
 1986 -2.597839 
 1987 -2.286181 
 1988 -2.351725 
 1989 -2.310798 
 1990 -2.055843 
 1991 -2.176688 
 1992 -2.200572 
 1993 -2.260463 
 1994 -2.203813 
 1995 -2.317433 
 1996 -2.172092 
 1997 -1.97409 
 1998 -1.886966 
 1999 -1.825432 
 2000 -1.682919 
 2001 -1.477048 
 2002 -1.653025 
 2003 -1.634676 
 2004 -1.667335 
 2005 -1.300009