Year	% of population
1989	46.4
1990	47.3
1991	41.9
1992	39.7
1993	38.9
1994	39.2
1995	39.8
1996	41.7
1997	37.6
1998	38.8
1999	38.6
2001	37.5
2002	38.1
2003	40.3
2004	40
2005	39.5
2006	38
2007	35.6
2008	35.2
2009	33.9
2010	34.2
2011	34.6
2012	36.8
2013	34.8
2014	34.8
2015	35.1
2016	35.1
2017	33.7
2018	34.1
2019	34.9