Year	% of population
1970	15.2
1975	13.5
1979	14
1984	14
1990	13
1996	14.2
1997	14
1998	13.5
1999	13.5
2000	13.5
2001	13.5
2002	12.2
2003	10.8
2004	10.7
2005	10.6
2006	11
2007	11
2008	11.3
2009	12.5
2010	12
2011	11.5
2012	11.5
2013	11.4
2014	11.4
2015	11.8
2016	11.7
2017	11.7
2018	11.2
2019	13.1
2020	12.7
2021	13.3