# year    value 
 1980 -4.485679 
 1981 -4.466521 
 1982 -4.433363 
 1983 -4.796378 
 1984 -4.634354 
 1985 -4.533095 
 1986 -4.539389 
 1987 -4.482116 
 1988 -4.349547 
 1989 -4.431432 
 1990 -4.333354 
 1991 -4.270892 
 1992 -4.709604 
 1993 -4.578601 
 1994 -4.510205 
 1995 -4.41596 
 1996 -4.27523 
 1997 -4.295363 
 1998 -4.227541 
 1999 -4.176888 
 2000 -4.089878 
 2001  -4.1106 
 2002 -3.992458 
 2003 -3.990111 
 2004 -4.088196 
 2005 -4.01696