# year    value 
 1979 14.01202 
 1980 14.15632 
 1981 14.02488 
 1982  14.0451 
 1983 13.98932 
 1984 13.45247 
 1985 14.06181 
 1986 13.81478 
 1987 13.96081 
 1988 13.94743 
 1989 14.11107 
 1990  14.0221 
 1991 13.88694 
 1992 13.38411 
 1993  13.8622 
 1994 14.03133 
 1995 13.70482 
 1996 13.80995 
 1997 14.02369 
 1998 14.19167 
 1999 14.10832 
 2000 13.72327 
 2001 13.97029 
 2002 13.92774 
 2003 14.11956 
 2004 14.18485 
 2005 14.13897 
 2006 14.17805 
 2007 13.98639 
 2008 14.21915 
 2009 14.31741 
 2010 14.00904 
 2011 14.10232 
 2012 14.17655 
 2013 14.51394 
 2014 14.42307 
 2015  14.3921 
 2016 14.29414 
 2017  14.5207 
 2018  14.4943