# year    value 
 1980 -0.1523272 
 1981 -0.1634963 
 1982 -0.293801 
 1983 -0.3905546 
 1984 -0.2630462 
 1985 -0.2532349 
 1986 -0.2536002 
 1987 -0.1680136 
 1988 -0.05296966 
 1989 -0.06142674 
 1990 0.01774312 
 1991 -0.1373865 
 1992 -0.3561631 
 1993 -0.2177042 
 1994 -0.2053479 
 1995 -0.1583358 
 1996 0.0001029422 
 1997 0.05072899 
 1998 0.09195331 
 1999 0.1032769 
 2000 0.1249085 
 2001 0.2231214 
 2002 0.2940951 
 2003 0.2000148 
 2004 0.2222902 
 2005 0.1411713