# year    value 
 1979 11.29337 
 1980 11.65885 
 1981 11.70589 
 1982 11.37127 
 1983 12.51807 
 1984 11.10725 
 1985 11.41027 
 1986 11.26323 
 1987  11.1711 
 1988 11.54934 
 1989 10.98908 
 1990 11.59522 
 1991 12.12433 
 1992 11.71189 
 1993 11.52816 
 1994 11.93714 
 1995 11.89865 
 1996 11.62493 
 1997  11.7299 
 1998 12.38779 
 1999 11.26045 
 2000 11.44031 
 2001 11.25765 
 2002 11.92916 
 2003 11.94401 
 2004 11.63811 
 2005 11.71467 
 2006 11.84991 
 2007 11.63603 
 2008 11.18334 
 2009 12.19258 
 2010 12.25895 
 2011 11.64879 
 2012 11.87579 
 2013 11.86888 
 2014 11.70982 
 2015 12.39861 
 2016 12.27642 
 2017 11.84851 
 2018 12.22628