Year	% of population
2001	4.4
2002	4.5
2003	4.5
2004	4.4
2005	4.3
2006	4.3
2007	4
2008	3.8
2009	3.6
2010	3.5
2011	3.4
2012	3.3
2013	3.1
2014	2.9
2015	2.8
2016	2.7
2017	2.6
2018	2.5
2019	2.5
2020	2.8
2021	3