Year % 2004 24.2 2005 28.1 2006 22.8 2007 22.3 2008 22.1 2009 21.5 2010 23.1 2011 23.2 2012 23.9 2013 24.4 2014 24 2015 23.8 2016 23.8 2017 23.9 2018 23.2 2019 23.3 2020 23.3 2021 24.1