# year    value 
 1979 13.17474 
 1980 13.85341 
 1981 13.60107 
 1982 13.69481 
 1983 13.74488 
 1984   13.497 
 1985  13.7622 
 1986  13.3417 
 1987  13.6919 
 1988 13.74869 
 1989   13.679 
 1990 13.86048 
 1991 13.52598 
 1992 12.82139 
 1993 13.50525 
 1994 13.62007 
 1995 13.56918 
 1996 13.71718 
 1997 13.60556 
 1998 13.76116 
 1999 13.92622 
 2000 13.32184 
 2001 13.50409 
 2002 13.87441 
 2003 13.72923 
 2004 13.94518 
 2005 13.72296 
 2006 14.27616 
 2007 14.01971 
 2008 14.14944 
 2009 13.71611 
 2010 13.52633 
 2011 14.06455 
 2012 14.24558 
 2013 14.05739 
 2014 14.51134 
 2015 13.87808 
 2016 13.72084 
 2017 14.18733 
 2018 14.04432