Year	% of population
2001	22.7
2002	20.3
2003	19.4
2004	19.6
2005	19.4
2006	18.3
2007	18.7
2008	18.2
2009	17.5
2010	15.8
2011	15.3
2012	15.7
2013	16.1
2014	16.2
2015	15.7
2016	14.8
2017	14.4
2018	14.1
2019	14.1
2020	13.5
2021	13.3