Year	% (national estimate)
1961	49.2
1971	43.73
1977	44.14
1979	44.1
1981	42.67
1982	42.47
1983	41.11
1984	42.34
1985	42.53
1986	42.17
1987	41.72
1988	41.94
1989	43.12
1990	44.61
1991	45.69
1992	44.25
1993	40.91
1994	44.12
1995	46.4
1996	47.3
1997	50.25
1998	51.5
2001	52.3
2002	54.82
2003	54.1
2005	46.266
2006	45.61
2007	44.461
2008	43.852
2009	42.82
2010	41.612
2011	40.656
2012	39.853
2016	34.883
2017	42.18
2020	37.19