Year % of population 2001 22.9 2002 20.9 2003 18.9 2004 18.5 2005 17.8 2006 17.4 2007 16.1 2008 15.4 2009 14.6 2010 14.5 2011 14.2 2012 13.7 2013 13.2 2014 13.1 2015 13.3 2016 13.6 2017 13.7 2018 14 2019 14.6 2020 15.5 2021 16.2