Year	% of population
1981	39.2
1982	39.6
1983	42.4
1984	41.9
1985	40.3
1986	34.5
1987	37.9
1988	38.7
1989	38.1
1990	39.5
1992	38.6
1993	38.7
1995	34.9
1996	35.9
1997	36
1998	35
1999	35.6
2001	34.6
2002	34.4
2003	34.5
2004	33.7
2005	33.1
2006	31.9
2007	31.7
2008	30.5
2009	30.2
2011	29.2
2012	29.2
2013	28.1
2014	27.7
2015	28
2016	28.7
2017	29.1
2018	29.1
2019	29.3
2020	23.5
2021	28.9
2022	27.2