# year    value 
 1979  11.8517 
 1980 11.53364 
 1981 11.76632 
 1982 10.36978 
 1983 11.73231 
 1984 10.18961 
 1985 9.008245 
 1986 10.22607 
 1987 11.89779 
 1988 11.83199 
 1989 11.46197 
 1990 12.10775 
 1991 10.86605 
 1992 11.06343 
 1993 10.21672 
 1994 11.22439 
 1995 11.85556 
 1996 10.35333 
 1997 11.51731 
 1998 12.31829 
 1999 12.38629 
 2000 10.23888 
 2001 12.58529 
 2002 10.85501 
 2003 11.71482 
 2004 11.45506 
 2005 12.25089 
 2006 11.04092 
 2007 12.19346 
 2008 12.03352 
 2009 11.53624 
 2010 11.94551 
 2011 12.12091 
 2012 12.47171 
 2013 11.22086 
 2014 11.95142 
 2015 12.80183 
 2016 13.19276 
 2017  12.3766 
 2018 11.11525