# year    value 
 1980 -8.349456 
 1981 -8.063168 
 1982 -8.135506 
 1983 -8.208262 
 1984 -8.341755 
 1985 -8.342037 
 1986 -7.935805 
 1987 -8.125369 
 1988 -7.997877 
 1989 -7.80286 
 1990 -7.381405 
 1991 -7.825518 
 1992 -7.911507 
 1993 -8.045405 
 1994 -8.130207 
 1995 -7.779284 
 1996 -7.804271 
 1997 -7.884874 
 1998 -7.700711 
 1999 -7.802162 
 2000 -7.913877 
 2001 -7.356071 
 2002 -7.63075 
 2003 -7.131629 
 2004 -7.058561 
 2005 -7.558623