# year    value 
 1980 -0.5107787 
 1981 -0.4185696 
 1982 -0.6536686 
 1983 -0.8380732 
 1984 -0.680797 
 1985 -0.5516892 
 1986 -0.6024845 
 1987 -0.3324626 
 1988 -0.3172479 
 1989 -0.2991907 
 1990 -0.1104346 
 1991 -0.1876517 
 1992 -0.4121091 
 1993 -0.3558667 
 1994 -0.3198997 
 1995 -0.2744603 
 1996 -0.1370728 
 1997 0.03858766 
 1998 0.1319224 
 1999 0.2175708 
 2000 0.2927716 
 2001 0.4391905 
 2002 0.4461902 
 2003 0.5044477 
 2004 0.514851 
 2005 1.974341