Year	% (national estimate)
1960	54.77
1970	55.85
1977	56.34
1978	55.47
1979	54.42
1980	53.39
1981	52.75
1982	52.45
1983	51.72
1984	51.53
1985	50.26
1986	46.604
1987	49.396
1988	49.68
1989	47.622
1990	47.043
1991	45.359
1992	44.508
1993	43.056
1994	43.239
1995	41.575
1996	40.582
1997	40.768
1998	41.06
1999	42.019
2000	43.111
2001	42.383
2002	43.632
2003	44.375
2004	44.886
2005	47.917
2006	48.389
2007	47.897
2008	47.718
2009	45.096
2010	42.754
2011	40.896
2012	38.969
2013	37.853
2014	35.886
2015	34.724
2016	33.096
2017	33.357
2018	33.007
2019	33.009
2020	29.953
2021	31.547
2022	32.726
2023	33.089