Year	% of population
2001	15
2002	15
2003	13.6
2004	11.7
2005	11.2
2006	11.5
2007	12.4
2008	13.3
2009	15.7
2010	17
2011	18.2
2012	18.5
2013	19.4
2014	20.7
2015	21.4
2016	21.7
2017	20.9
2018	19.8
2019	18.5
2020	18.1
2021	18.2