Year % 2000 14.9 2001 14.6 2002 14.9 2003 14.9 2004 15.1 2005 14.6 2006 14.8 2007 15.1 2008 15.4 2009 15.3 2010 15.5 2011 15.5 2012 14.7 2013 14.3 2014 14.8 2015 14.7 2016 14.7 2017 14.7 2018 14.6 2019 14.6