# year    value 
 1980 0.7294411 
 1981 0.7305653 
 1982 0.6495256 
 1983 0.5469837 
 1984 0.6225224 
 1985 0.6706789 
 1986 0.7517664 
 1987  0.75883 
 1988 0.7585254 
 1989 0.8052009 
 1990 0.8122705 
 1991 0.8833931 
 1992 0.5639906 
 1993 0.6475899 
 1994 0.7412598 
 1995 0.7155799 
 1996 0.8082728 
 1997 0.8803674 
 1998 0.9146723 
 1999 0.9334445 
 2000 0.9236533 
 2001 1.039961 
 2002 1.098905 
 2003 1.060506 
 2004 0.968054 
 2005 1.125565