Year	% of population
2001	27.1
2002	24.8
2003	24.6
2004	23.7
2005	22.9
2006	21.9
2007	21.4
2008	20.9
2009	20.7
2010	19.9
2011	19.1
2012	19
2013	19.4
2014	19.8
2015	19.3
2016	18.3
2017	17.6
2018	17.4
2019	17.5
2020	17.9
2021	17.8