# year    value 
 1980 10.71795 
 1981 10.94016 
 1982 10.51888 
 1983 10.15903 
 1984 10.58942 
 1985 10.73848 
 1986 10.86283 
 1987 10.67725 
 1988 10.85242 
 1989 10.99582 
 1990 10.94714 
 1991 11.03903 
 1992 10.27007 
 1993 10.52537 
 1994 11.00664 
 1995 10.88702 
 1996 11.01546 
 1997 11.10134 
 1998  11.4655 
 1999 11.25123 
 2000  11.4576 
 2001 11.43771 
 2002 11.48356 
 2003 11.58347 
 2004 11.57009 
 2005 11.44592