# year    value 
 1980 -0.5124974 
 1981 -0.4230349 
 1982 -0.6313188 
 1983 -0.7631352 
 1984 -0.6477962 
 1985 -0.5911388 
 1986 -0.557353 
 1987 -0.308566 
 1988 -0.2673286 
 1989 -0.2459154 
 1990 -0.06187068 
 1991 -0.203436 
 1992 -0.3621083 
 1993 -0.2835577 
 1994 -0.3731774 
 1995 -0.3085133 
 1996 -0.1301937 
 1997 0.04488117 
 1998 0.1551108 
 1999 0.1493093 
 2000 0.2770654 
 2001 0.4704126 
 2002 0.4031701 
 2003 0.4367666 
 2004 0.4479043 
 2005 2.038633