# year    value 
 1979 11.39277 
 1980 10.68106 
 1981 11.42885 
 1982 11.87305 
 1983 11.85174 
 1984 11.04483 
 1985 10.94167 
 1986 11.27139 
 1987 11.20266 
 1988 11.98311 
 1989 12.05128 
 1990 12.21817 
 1991   11.218 
 1992 12.18609 
 1993  11.6475 
 1994 12.87521 
 1995 11.89792 
 1996 11.00611 
 1997 12.03099 
 1998 12.04413 
 1999  12.2102 
 2000 12.90982 
 2001 12.20062 
 2002 12.68482 
 2003 12.65003 
 2004 11.99009 
 2005 11.64407 
 2006 12.39008 
 2007 12.80603 
 2008 12.53188 
 2009 12.60738 
 2010  11.5794 
 2011 12.73697 
 2012 12.60579 
 2013  12.1811 
 2014 13.28475 
 2015 13.10047 
 2016 12.65632 
 2017  12.7558 
 2018  13.4475 
 2019 6.109882