# year    value 
 1979  24.8934 
 1980 24.79536 
 1981 24.47727 
 1982 24.39875 
 1983 25.18291 
 1984 24.49997 
 1985 24.10561 
 1986 24.43931 
 1987 24.80099 
 1988 24.62069 
 1989 24.75637 
 1990 24.81123 
 1991 24.57021 
 1992 24.58692 
 1993 24.31087 
 1994 24.48255 
 1995 24.90666 
 1996 24.55738 
 1997 24.43383 
 1998 25.07905 
 1999 24.46467 
 2000 24.44616 
 2001 24.58702 
 2002 24.65175 
 2003 24.97394 
 2004  24.8003 
 2005 25.07815 
 2006 24.78445 
 2007 25.09218 
 2008 24.62248 
 2009 24.87598 
 2010  25.1459 
 2011 24.74102 
 2012 24.92902 
 2013 25.05554 
 2014 25.06039 
 2015 24.78442 
 2016 25.78419 
 2017 25.19304 
 2018 25.00421 
 2019 24.80503