Year	% of population
2004	18.1
2005	18.9
2006	15.8
2007	18.2
2008	18.6
2009	19.5
2010	20.6
2011	18.6
2012	18.6
2013	16.9
2014	16.3
2015	14.6
2016	15.4
2017	15.4
2018	14.4
2019	14.2
2020	15.1
2021	14.7