# year    value 
 1980 0.3436038 
 1981 0.3777696 
 1982 0.156841 
 1983 0.09116403 
 1984 0.228943 
 1985 0.3142007 
 1986  0.28181 
 1987 0.3974802 
 1988 0.4710651 
 1989 0.5342746 
 1990 0.594692 
 1991 0.3791727 
 1992 0.172994 
 1993 0.3171939 
 1994 0.427389 
 1995 0.5413417 
 1996  0.61368 
 1997 0.7041978 
 1998 0.7304703 
 1999 0.7973335 
 2000 0.8609307 
 2001 0.925604 
 2002 0.9810133 
 2003 0.9585214 
 2004 0.9672413 
 2005 1.029351