Year	% (national estimate)
1977	71.54
1978	69.32
1979	67.3
1980	64.35
1981	61.89
1982	60.33
1983	58.72
1984	56.19
1986	54.867
1987	55.716
1988	55.963
1989	57.195
1990	58.147
1991	57.476
1992	57.233
1993	53.555
1994	52.199
1995	52.729
1996	52.969
1997	54.031
1998	55.8
1999	57.94
2000	59.36
2001	60.539
2002	60.844
2003	61.261
2004	61.595
2005	63.248
2006	64.068
2007	64.111
2008	61.791
2009	55.863
2010	54.166
2011	52.759
2012	49.98
2013	48.836
2014	49.737
2015	51.359
2016	52.649
2017	53.877
2018	54.974
2019	55.54
2020	53.494
2021	54.556
2022	55.741
2023	56.319