# year    value 
 1980 12.53329 
 1981 12.62794 
 1982 12.41098 
 1983 12.06874 
 1984 12.37577 
 1985 12.55488 
 1986 12.57713 
 1987 12.52315 
 1988 12.66739 
 1989 12.75953 
 1990  12.7311 
 1991 12.76948 
 1992 12.14097 
 1993 12.40026 
 1994 12.70725 
 1995 12.75921 
 1996 12.76385 
 1997 12.90142 
 1998 13.05664 
 1999 13.01854 
 2000 13.16331 
 2001 13.23998 
 2002 13.15559 
 2003 13.26012 
 2004 13.26019 
 2005 13.25035