Year % 2000 29 2001 28.2 2002 27.3 2003 26.6 2004 25.8 2005 25 2006 24.3 2007 23.5 2008 22.9 2009 22.3 2010 21.9 2011 21.9 2012 22.1 2013 22.3 2014 22.6 2015 23 2016 23.5 2017 24 2018 24.2 2019 24.5