# year    value 
 1980  13.2419 
 1981 13.56828 
 1982 13.01534 
 1983 13.25976 
 1984 13.20848 
 1985  13.1503 
 1986 13.38832 
 1987 13.15041 
 1988 13.56221 
 1989 13.39622 
 1990 13.96011 
 1991 13.51938 
 1992 13.34351 
 1993 13.46662 
 1994  13.5934 
 1995 13.59701 
 1996 13.24177 
 1997 13.53139 
 1998 13.97356 
 1999 13.49769 
 2000 13.91951 
 2001 13.89688 
 2002 13.89188 
 2003 13.76678 
 2004 13.80871 
 2005 14.08869 
 2006 13.79045 
 2007 14.13742 
 2008 13.97043 
 2009 13.80978 
 2010  14.2557 
 2011 13.88026 
 2012 14.06912 
 2013 13.83502 
 2014 14.11122 
 2015 14.15313 
 2016 14.66578 
 2017 14.29441 
 2018 14.10855