# year    value 
 1979 10.01888 
 1980  10.8388 
 1981 11.42665 
 1982 9.804291 
 1983 10.38794 
 1984 10.26438 
 1985 9.765004 
 1986 11.05198 
 1987 11.11211 
 1988  10.9854 
 1989 10.48978 
 1990 10.92106 
 1991 10.72738 
 1992 10.94654 
 1993 9.894652 
 1994 11.07695 
 1995 10.85103 
 1996 10.43979 
 1997 10.50513 
 1998 11.02448 
 1999 11.15675 
 2000 11.06701 
 2001 11.15432 
 2002 10.80792 
 2003 11.37209 
 2004 10.98531 
 2005 11.33396 
 2006 11.66595 
 2007 11.34144 
 2008 10.68099 
 2009 10.64724 
 2010 10.93031 
 2011 10.88483 
 2012 12.27663 
 2013 10.68857 
 2014 11.22704 
 2015 12.03517 
 2016 12.10798 
 2017 11.88736 
 2018 11.42091