# year    value 
 1980 0.5013227 
 1981 0.4612757 
 1982 0.2614117 
 1983 0.2926251 
 1984 0.4114361 
 1985 0.3931741 
 1986 0.4042525 
 1987 0.4888959 
 1988 0.6012607 
 1989 0.635648 
 1990 0.7025622 
 1991 0.3298583 
 1992 0.3422363 
 1993 0.4244719 
 1994 0.4743926 
 1995 0.5371187 
 1996 0.6806014 
 1997 0.7383933 
 1998 0.7332124 
 1999 0.7605305 
 2000 0.8576633 
 2001 0.9352434 
 2002 0.9393032 
 2003 0.8888595 
 2004 0.903557 
 2005 0.9732334