Year	% (national estimate)
1960	50.1
1961	49
1962	49.5
1963	48.5
1964	49
1965	50.199999999999996
1966	52.2
1967	52.7
1968	52.699999999999996
1969	54
1970	53.2
1971	52.3
1972	54.3
1973	57
1974	57.2
1975	54.2
1976	55.697786705755036
1977	57.40633415715284
1978	59.45673939984592
1979	60.42548344076017
1980	58.719858449501565
1981	57.88890887964386
1982	55.27329848752967
1983	55.4969787710253
1984	58.08220286547325
1985	58.87667009626173
1986	59.50220379348685
1987	60.191185421246445
1988	60.96485616257202
1989	61.413332414903465
1990	59.945403893852294
1991	57.21282154119471
1992	56.51064908934183
1993	56.82547203398843
1994	57.770735643201455
1995	57.8984561525258
1996	57.25239523915584
1997	57.541315143794115
1998	58.364021866505986
1999	58.57000906990696
2000	59.33357016726284
2001	57.58330193871034
2002	55.860795739451646
2003	54.307709412104
2004	54.27360486969918
2005	54.26558227353237
2006	54.73062682730923
2007	53.8229728271611
2008	52.10103346930551
2009	47.754834966360015
2010	46.04434739354301
2011	46.49686466252928
2012	46.921674794851995
2013	47.45015678938352
2014	48.49195606236359
2015	49.39856230758987
2016	50.085753799160976
2017	51.058840874417214
2018	51.169583373277916
2019	51.91111714602831
2020	46.229532707273904
2021	50.62279323377268
2022	51.7701568898133
2023	52.371336660548536