Year	% (national estimate)
1960	78.9
1961	77.6
1962	77.7
1963	77.1
1964	77.3
1965	77.5
1966	77.9
1967	78
1968	77.8
1969	77.6
1970	76.2
1971	74.9
1972	75
1973	75.5
1974	74.9
1975	71.7
1976	72.06775863507539
1977	72.7063524448197
1978	73.61989797178968
1979	73.7258854579179
1980	72.08363371259499
1981	71.45217182209294
1982	68.93809509025792
1983	68.65751276335071
1984	70.42724101089438
1985	70.68046379970328
1986	70.8571403261409
1987	71.37875941485996
1988	71.89229868467092
1989	72.3577938124196
1990	71.78564704696066
1991	70.04398128033637
1992	69.30802107077727
1993	69.4447385191314
1994	69.9405825236865
1995	70.26733452882273
1996	70.35123091628599
1997	70.78615758778653
1998	71.01295593033748
1999	71.14581193164213
2000	71.43140669711275
2001	70.4588011504521
2002	69.43859849495763
2003	68.76415866341843
2004	69.03716673830941
2005	69.40765762210994
2006	69.83596871861313
2007	69.58328319697365
2008	68.4513183885456
2009	64.62859840775643
2010	63.8788908763321
2011	64.09342152014754
2012	64.5593442114721
2013	64.5767169648829
2014	64.96908136387962
2015	65.37851001312023
2016	65.70652830258734
2017	66.01069443684716
2018	66.29360763006709
2019	66.54288999872492
2020	62.36822499673993
2021	63.96268773728241
2022	65.49623103358613
2023	65.5602748684456