# year    value 
 1980 0.0102773 
 1981 0.03664802 
 1982 -0.05058773 
 1983 -0.2527168 
 1984 -0.08669002 
 1985 -0.06186266 
 1986 -0.1087635 
 1987 -0.0136744 
 1988 0.1302125 
 1989 0.0948829 
 1990 0.1689509 
 1991 0.1689262 
 1992 -0.2372446 
 1993 -0.01762387 
 1994 -0.02865849 
 1995 -0.006408831 
 1996 0.150011 
 1997 0.211299 
 1998 0.2348972 
 1999 0.2855337 
 2000 0.249959 
 2001 0.3770877 
 2002 0.4918775 
 2003 0.3378129 
 2004 0.3594814 
 2005 0.4728776