Year	% (national estimate)
1960	56.4
1961	55.8525520294027
1962	55.79999999999999
1963	55.2
1964	55.300000000000004
1965	55.8
1966	57.1
1967	57.7
1968	57.699999999999996
1969	58.9
1970	59.802203875843404
1971	59.642103782015354
1972	61.8
1973	63.7
1974	64.9
1975	64.6
1976	65.12915149205574
1977	66.48928181878894
1978	67.93841490222057
1979	68.48117804863891
1980	68.14806770515007
1981	67.86001265694968
1982	67.21226826248635
1983	67.15212627920234
1984	67.72721190216127
1985	68.33052920567947
1986	68.714597261316
1987	68.5895226402377
1988	68.61554328121358
1989	68.85173617835984
1990	67.55658933931994
1991	66.2058029605438
1992	66.10546861835836
1993	65.93741572569812
1994	66.2914915137952
1995	66.11921676716435
1996	65.36821050101976
1997	65.3001686057512
1998	65.48105544007959
1999	65.28396751218689
2000	65.66861217498288
2001	64.53992722642573
2002	63.592199644816716
2003	62.10193838835331
2004	61.68141086975844
2005	61.260817642855585
2006	61.235262097663046
2007	60.20163004920902
2008	59.67270355125762
2009	57.76274049212919
2010	56.1516538414925
2011	55.97607684206301
2012	55.84108142183122
2013	56.01701552236297
2014	55.980759180490224
2015	55.97420277985491
2016	56.06340722019399
2017	56.39044712344082
2018	56.134362982770554
2019	56.82909004181794
2020	54.69906708598893
2021	56.33423407191971
2022	56.47971117107821
2023	57.07501028433278