# year    value 
 1980 11.79161 
 1981  11.8874 
 1982 11.65753 
 1983 11.35974 
 1984 11.68593 
 1985 11.81194 
 1986 11.82846 
 1987 11.83866 
 1988 11.92745 
 1989 12.03849 
 1990 11.98548 
 1991 12.05242 
 1992 11.42412 
 1993 11.68421 
 1994 11.98842 
 1995 12.02986 
 1996 12.05644 
 1997 12.20472 
 1998  12.3122 
 1999 12.26874 
 2000 12.42413 
 2001 12.46082 
 2002  12.4386 
 2003  12.5058 
 2004 12.49842 
 2005 12.51007