# year    value 
 1980 -3.481755 
 1981 -3.598648 
 1982 -3.659343 
 1983 -3.80706 
 1984 -3.572078 
 1985 -3.742589 
 1986 -3.632931 
 1987 -3.446529 
 1988 -3.421575 
 1989 -3.427975 
 1990 -3.315288 
 1991 -3.501437 
 1992 -3.787894 
 1993 -3.596629 
 1994 -3.63441 
 1995 -3.500728 
 1996 -3.176714 
 1997 -3.290384 
 1998 -3.147228 
 1999 -3.118108 
 2000 -3.225266 
 2001 -3.040919 
 2002 -3.018034 
 2003 -3.148025 
 2004 -2.968413 
 2005 -2.939095