Year	% of population
2001	3.2
2002	3.6
2003	4.2
2004	4.6
2005	4.4
2006	4.1
2007	4.1
2008	4.4
2009	4.5
2010	4.4
2011	4.1
2012	4
2013	4
2014	4
2015	3.9
2016	3.8
2017	3.8
2018	3.4
2019	2.8
2020	2.5
2021	2.5