# year    value 
 1980 0.6984277 
 1981 0.693154 
 1982 0.6169472 
 1983 0.5121537 
 1984 0.5876005 
 1985 0.6331621 
 1986 0.7163377 
 1987 0.7302893 
 1988 0.729848 
 1989 0.7751005 
 1990 0.7867036 
 1991 0.8527752 
 1992 0.5361905 
 1993 0.6166725 
 1994 0.6993369 
 1995 0.6751782 
 1996 0.7733841 
 1997 0.8502678 
 1998 0.888904 
 1999  0.90416 
 2000 0.8941085 
 2001 1.011286 
 2002 1.074946 
 2003 1.025341 
 2004 0.9409251 
 2005 1.086651