Year	% (national estimate)
1960	71.7
1961	69.94240966094938
1962	70
1963	69.1
1964	68.8
1965	69
1966	69
1967	69.3
1968	68.3
1969	68.8
1970	69.40198799205214
1971	69.15565304340275
1972	71.3
1973	72.9
1974	73.7
1975	72.4
1976	72.49782544449542
1977	73.67320926532166
1978	74.47848207852502
1979	74.73470413523451
1980	74.27128554801112
1981	73.68900556783777
1982	72.4067471636317
1983	72.30734426773324
1984	72.59606359764159
1985	72.82282728730114
1986	72.93017508152154
1987	72.37073975622008
1988	72.46605785239622
1989	73.07652537166886
1990	71.85919779745815
1991	70.36680370809974
1992	70.23525866063999
1993	69.84357849535053
1994	69.91753485539121
1995	69.8491509454983
1996	68.51692293351056
1997	67.9807749127278
1998	67.88265185117655
1999	67.7640384562082
2000	68.32093009179789
2001	66.93744223267178
2002	65.7021803464806
2003	64.26652174097624
2004	63.962800394413364
2005	63.2377590719734
2006	63.67608905031572
2007	62.17499783502351
2008	61.725821522913485
2009	59.220216046200036
2010	57.554177597795714
2011	57.4530967104834
2012	57.30052156945453
2013	57.40314392955549
2014	57.22196860895683
2015	57.04761601568845
2016	57.265809313699094
2017	57.48757030812991
2018	56.79368233616977
2019	57.46319176296216
2020	55.35566095853341
2021	57.22844528690065
2022	57.24536045715841
2023	57.36124257247454