Year % 2004 14.6 2005 14.6 2006 14.7 2007 14.7 2008 14.9 2009 14.6 2010 14.7 2011 14.7 2012 14.6 2013 14.4 2014 14.5 2015 14.5 2016 14.7 2017 14.8 2018 14.6 2019 14.7 2020 14.8 2021 14.7