Year	% of population
1986	32.1
1990	31.2
1994	29.1
1998	29.5
2005	24.4
2006	25.5
2009	24.7
2011	19.8
2012	18.9
2013	18.2
2014	19.9
2015	19.4
2016	19.6
2017	20.2
2018	20.8
2019	21.9
2020	21.5
2021	21.1
2022	20