Year % 2001 6.31 2003 6.31 2004 6.27 2005 6.27 2006 6.27 2007 6.26 2008 6.36 2009 6.36 2010 6.36 2011 6.36 2012 6.36 2013 6.36 2014 6.36 2015 6.32 2016 6.32 2020 6.32 2021 6.32