Year	% (national estimate)
1960	82.08
1965	78.47
1970	69.82
1974	65.28
1976	65.01
1977	64.94
1978	64.99
1979	64.91
1981	71.74
1983	68.278
1984	76.769
1985	78.771
1986	78.552
1987	76.299
1988	78.56
1989	79.324
1990	76.505
1991	75.386
1992	72.963
1993	71.029
1994	72.097
1995	76.993
1996	76.606
1997	77.655
1998	71.528
1999	76.743
2000	75.173
2001	69.354
2002	70.583
2003	68.094
2004	68.971
2005	69.996
2006	70.543
2007	72.019
2008	69.913
2009	68.497
2010	64.014
2011	63.397
2012	61.029
2013	57.276
2014	57.755
2015	58.055
2016	57.926
2017	59.571
2018	59.358
2019	60.5
2020	60.078
2021	60.867
2022	62.678
2023	63.408