# year    value 
 1979 10.72001 
 1980 11.87687 
 1981 12.42592 
 1982 10.84591 
 1983 11.42478 
 1984 11.46644 
 1985 10.76412 
 1986 12.02721 
 1987 12.25834 
 1988 11.97841 
 1989 11.26281 
 1990 12.09064 
 1991 11.88451 
 1992 11.79881 
 1993 10.77883 
 1994 11.90802 
 1995 11.65894 
 1996 10.98956 
 1997 11.39223 
 1998 12.34844 
 1999 12.29982 
 2000   12.003 
 2001 12.12339 
 2002 11.67846 
 2003 12.08038 
 2004 11.87509 
 2005 12.36893 
 2006 12.85683 
 2007 12.19393 
 2008 11.54886 
 2009 11.45262 
 2010 11.89624 
 2011 12.04618 
 2012 13.38243 
 2013 11.50049 
 2014 11.71525 
 2015 12.85564 
 2016 13.17021 
 2017 12.79603 
 2018 12.02352 
 2019 0.8901612