# year    value 
 1980 8.133201 
 1981  8.31304 
 1982 8.136588 
 1983 7.762158 
 1984 8.109755 
 1985 8.097078 
 1986 8.300692 
 1987 8.282027 
 1988 8.356126 
 1989 8.460625 
 1990  8.29568 
 1991 8.125352 
 1992 7.957702 
 1993 8.044902 
 1994 8.433574 
 1995 8.497079 
 1996 8.719681 
 1997 8.666333 
 1998 8.826614 
 1999 8.668906 
 2000 8.975468 
 2001 9.201047 
 2002 8.813787 
 2003 9.092018 
 2004 8.997698 
 2005 9.058847