# year    value 
 1980 -0.2336677 
 1981 -0.1681514 
 1982 -0.4332133 
 1983 -0.4439685 
 1984 -0.3455444 
 1985 -0.2577359 
 1986 -0.1529285 
 1987 -0.06147056 
 1988 -0.07039399 
 1989 0.06033607 
 1990 -0.01884447 
 1991 -0.2263768 
 1992 -0.4085029 
 1993 -0.1921785 
 1994 -0.03672426 
 1995 -0.02673386 
 1996 0.1743105 
 1997 0.1138912 
 1998 0.2275646 
 1999 0.240922 
 2000 0.3010274 
 2001  0.44106 
 2002 0.3458602 
 2003 0.3991689 
 2004 0.4014174 
 2005 0.4929191