Year % of population 2001 15.8 2002 16.1 2003 16.4 2004 16.5 2005 16.4 2006 16.3 2007 16.2 2008 16.1 2009 19.8 2010 23.8 2011 28.1 2012 30.4 2013 33 2014 34.8 2015 35.1 2016 34 2017 32.9 2018 33.1 2019 35.3 2020 36.8 2021 37.9