Year % 1996 33.1 1997 33.1 1998 33.1 1999 33.1 2000 33.1 2001 33.1 2002 33.1 2003 33.1 2004 33.1 2005 32.94 2006 32.94 2007 33 2008 33 2010 33 2011 33 2012 32.97 2013 32.97 2015 32.97 2016 32.97 2017 33.04 2018 33.04 2020 33.04 2021 33.04