Year	% (national estimate)
1961	49.68
1966	54.55
1971	62.17
1975	63
1976	63.87
1979	59
1980	60.63
1981	61.95
1982	61.22
1983	62.92
1984	64.03
1985	60.57
1986	61.45
1987	59.77
1988	58.33
1989	56.88
1990	55.72
1991	55.2
1992	53.87
1993	52.14
1994	51.61
1995	49.35
1996	49.61
1997	48.72
1998	49.12
2000	44.73
2001	45.45
2002	45.38
2003	44.4
2004	44.66
2005	44.79
2006	44.08
2007	44.47
2008	42.53
2009	40.28
2010	36.731
2011	37.049
2012	37.578
2013	39.963
2014	39.263
2015	41.427
2016	41.936
2017	41.518
2018	40.943
2019	40.46
2020	36.567
2021	35.336
2022	32.457
2023	31.101