Year	% of population
2004	21.7
2005	18.9
2006	15.5
2007	15.5
2008	15.8
2009	20.2
2010	20.7
2011	16.9
2012	18
2013	17.1
2014	17.7
2015	17
2016	18.1
2017	15.6
2018	15.1
2019	13.8
2020	12.5
2021	13.1