# year    value 
 1980 0.2769887 
 1981 0.3103491 
 1982 0.09260758 
 1983 0.02037341 
 1984 0.1576817 
 1985 0.242935 
 1986 0.2239311 
 1987 0.3384297 
 1988 0.4180347 
 1989 0.4706783 
 1990 0.5274129 
 1991 0.3145562 
 1992 0.1012026 
 1993 0.2544644 
 1994 0.3719516 
 1995 0.4794319 
 1996 0.5524085 
 1997 0.6391878 
 1998 0.6814049 
 1999 0.7324247 
 2000 0.805007 
 2001 0.8700659 
 2002 0.9174109 
 2003 0.8986483 
 2004 0.9050453 
 2005 0.9681813