Year	% of population
2001	3.9
2002	4.1
2003	4.4
2004	4.8
2005	4.8
2006	5
2007	4.6
2008	4.4
2009	4.4
2010	4.6
2011	4.8
2012	4.3
2013	3.8
2014	3.8
2015	3.7
2016	3.8
2017	3.1
2018	2.8
2019	2.7
2020	2.5
2021	2.5