Year	% of population
2004	22.5
2005	20.4
2006	18.6
2007	16.9
2008	16.1
2009	16.7
2010	16.3
2011	16.4
2012	16.5
2013	16.4
2014	16.4
2015	16.1
2016	12.8
2017	12.2
2018	12.4
2019	11
2020	11.5
2021	10.6