Year % 1995 28.36 1997 28.3 1998 28.36 1999 28.3 2000 28.3 2001 28.3 2002 28.3 2003 28.3 2004 28.23 2005 28.23 2006 28.23 2007 28.35 2008 28.35 2009 28.35 2010 28.35 2011 28.35 2012 28.35 2013 28.35 2014 28.31 2015 28.23 2016 28.23 2017 28.23 2018 28.23 2019 28.2