# year    value 
 1980 0.6636593 
 1981 0.5888888 
 1982  0.37473 
 1983 0.4107682 
 1984 0.5220118 
 1985 0.4898357 
 1986 0.5303283 
 1987 0.6424975 
 1988 0.6649311 
 1989 0.7890207 
 1990 0.8269562 
 1991 0.4369158 
 1992 0.4836637 
 1993 0.5308294 
 1994 0.6006992 
 1995 0.6791787 
 1996 0.7943777 
 1997 0.8704635 
 1998 0.8829668 
 1999 0.9017866 
 2000 0.9820709 
 2001  1.12695 
 2002 1.084597 
 2003 1.029987 
 2004 1.102962 
 2005 1.151415