# year    value 
 1980 -4.270958 
 1981 -4.255214 
 1982 -4.21485 
 1983 -4.57069 
 1984 -4.418017 
 1985 -4.310801 
 1986 -4.322557 
 1987 -4.259583 
 1988 -4.134344 
 1989 -4.217044 
 1990 -4.115374 
 1991 -4.06274 
 1992 -4.483376 
 1993 -4.357083 
 1994 -4.289045 
 1995 -4.214597 
 1996 -4.059836 
 1997 -4.082987 
 1998 -4.010668 
 1999 -3.96542 
 2000 -3.878225 
 2001 -3.899437 
 2002 -3.773988 
 2003  -3.7767 
 2004 -3.872754 
 2005 -3.799481