Year % of population 2001 19 2002 19 2003 18.9 2004 19.1 2005 19.3 2006 19.1 2007 18.5 2008 17.4 2009 15.6 2010 13.2 2011 11 2012 9.6 2013 8.4 2014 7.9 2015 7.3 2016 6.7 2017 6 2018 5.9 2019 6 2020 6.1 2021 5.9