Year % 2000 26 2001 25.5 2002 24.9 2003 24.5 2004 24.1 2005 23.6 2006 23.3 2007 22.9 2008 22.6 2009 22.3 2010 22 2011 21.9 2012 21.8 2013 21.7 2014 21.6 2015 21.6 2016 21.6 2017 21.6 2018 21.6 2019 21.7