Year	% (national estimate)
1977	67.85
1979	66.57
1980	64.21
1981	63.43
1982	61.14
1983	61.09
1985	60.798
1986	58.67
1987	65.749
1988	64.962
1989	65.48
1990	66.855
1991	67.02
1992	67.496
1993	66.344
1994	65.809
1995	66.103
1996	66.741
1997	68.424
1998	69.763
1999	70.228
2000	71.589
2001	72.168
2002	72.42
2003	70.728
2004	69.915
2005	67.874
2006	68.269
2007	69.537
2008	70.276
2009	69.386
2010	67.91
2011	67.254
2012	67.003
2013	65.757
2014	65.415
2015	65.566
2016	65.693
2017	66.322
2018	66.962
2019	67.511
2020	66.721
2021	68.419
2022	69.956
2023	70.638