Year % 2000 36.8 2001 35.1 2002 34 2003 33 2004 32.3 2005 31.6 2006 30.8 2007 29.7 2008 28.9 2009 28.3 2010 27.9 2011 27.5 2012 27.2 2013 26.8 2014 26.3 2015 25.8 2016 25.5 2017 25.2 2018 25.1 2019 25