Year	% (national estimate)
1960	75.06
1970	63.23
1980	51.27
1981	51.39
1982	51.08
1983	49.03
1984	50.31
1985	54.93
1986	52.91
1988	52.78
1989	52.66
1990	52.53
1991	50.94
1992	50.28
1993	54.23
1994	54.03
1995	50.58
1996	55.604
1997	53.233
1998	51.504
1999	50.477
2000	47.662
2001	46.377
2002	45.74
2003	44.204
2004	43.645
2005	42.656
2006	43.829
2007	44.138
2008	46.809
2009	44.585
2010	44.411
2011	44.689
2012	43.022
2013	41.751
2014	42.105
2015	41.893
2016	40.272
2017	39.65
2018	38.01
2019	35.715
2020	30.608
2021	30.536
2022	33.291
2023	33.67