# year    value 
 1980 -0.1681481 
 1981 0.05458019 
 1982 0.09736545 
 1983 -0.5204663 
 1984 -0.2371685 
 1985 -0.1911784 
 1986 -0.123344 
 1987 0.03432735 
 1988 0.2551906 
 1989 0.1900533 
 1990 0.1222334 
 1991 0.02658876 
 1992 -0.1669549 
 1993 -0.298164 
 1994 0.1026946 
 1995 0.1012417 
 1996 0.2852271 
 1997 0.5330795 
 1998 0.3409237 
 1999 0.6493243 
 2000 0.5779092 
 2001 0.4710655 
 2002 0.7718023 
 2003 0.5955691 
 2004 0.4234043 
 2005 0.8030371