Year	% (national estimate)
1961	76.48
1971	63.93
1977	62.35
1979	62.45
1981	61.34
1982	61.45
1983	59.46
1984	59.9
1985	61.4
1986	61.27
1987	61.03
1988	61.49
1989	62.08
1990	62.22
1991	63.06
1992	61.18
1993	57.36
1994	61.88
1995	63.44
1996	63.4
1997	65.68
1998	66.6
2001	65.26
2002	67.24
2003	65.4
2005	58.412
2006	58.317
2007	57.254
2008	56.637
2009	55.341
2010	54.338
2011	53.079
2012	52.057
2016	46.235
2017	53.552
2020	45.59