Year	% of population
1979	31.7
1989	37.3
1991	36
1995	34.6
1997	33.4
1998	32.7
1999	32.3
2000	32.1
2001	34.2
2002	32.7
2003	32
2004	32.1
2005	31.6
2006	31.5
2007	30.7
2008	28.5
2009	27.7
2010	27.5
2011	27.1
2012	26.8
2013	27.2
2014	26.9
2015	26.3
2016	26.4
2017	26.7
2018	25.9
2019	25.8
2021	25.2
2023	25.4