Year % 2001 14.02 2002 8.29 2004 9.16 2005 8.29 2006 7.94 2007 7.4 2008 7.39 2009 6.97 2010 6.51 2011 6.5 2012 6.49 2013 6.38 2014 6.4 2015 6.38 2016 6.35 2017 6.39 2018 6.39 2019 6.39 2020 6.39 2021 6.35