Year % 1995 22.9 2000 23.1 2003 23.3 2004 23 2005 22.7 2006 22.6 2007 22.6 2008 22.5 2009 22.5 2010 22.9 2011 23.3 2012 23.2 2013 23.2 2014 23.3 2015 23.5 2016 23.2 2017 23 2018 23.1 2019 23.1 2020 23 2021 23.1