# year    value 
 1980 1.494535 
 1981 1.534108 
 1982 1.471273 
 1983 1.262151 
 1984 1.407072 
 1985 1.412685 
 1986 1.372531 
 1987 1.491322 
 1988 1.614562 
 1989 1.530141 
 1990 1.657002 
 1991 1.681131 
 1992 1.316443 
 1993 1.432668 
 1994 1.389533 
 1995  1.43784 
 1996 1.624478 
 1997 1.688746 
 1998 1.746156 
 1999 1.725477 
 2000 1.754473 
 2001 1.796763 
 2002 1.955374 
 2003 1.860871 
 2004 1.841603 
 2005 1.942467