# year    value 
 1980  0.58521 
 1981 0.6054753 
 1982 0.5145173 
 1983 0.2989267 
 1984 0.425835 
 1985 0.4934595 
 1986 0.4629145 
 1987 0.533353 
 1988 0.6984141 
 1989 0.6810235 
 1990 0.7260901 
 1991 0.7488669 
 1992 0.2613816 
 1993 0.4619533 
 1994 0.5541059 
 1995 0.5939672 
 1996 0.7080702 
 1997 0.7793254 
 1998 0.8560552 
 1999 0.8879884 
 2000 0.8818423 
 2001 0.9333124 
 2002 1.047826 
 2003 1.002837 
 2004 1.024859 
 2005 1.036094