# year    value 
 1980 0.669579 
 1981 0.7464122 
 1982 0.5727205 
 1983 0.3532306 
 1984 0.5430437 
 1985 0.7292255 
 1986 0.6098899 
 1987 0.7401218 
 1988 0.8040492 
 1989 0.8717361 
 1990 0.8690795 
 1991 0.8439698 
 1992 0.3772808 
 1993 0.6426432 
 1994 0.8700243 
 1995 0.9577327 
 1996 0.9421403 
 1997 1.125796 
 1998 1.097226 
 1999  1.25173 
 2000 1.288699 
 2001 1.302947 
 2002 1.418174 
 2003 1.414616 
 2004   1.3765 
 2005 1.418908