Year	% (national estimate)
1960	51.24
1970	49.53
1973	61.94
1976	58.28
1980	55.33
1985	63.78
1986	63.99
1987	64.84
1988	64.28
1989	65.654
1990	65.339
1991	63.95
1992	68.189
1993	66.38
1995	65.112
1996	62.678
1997	63.421
1998	63.307
1999	63.772
2001	62.986
2002	64.475
2003	64.037
2004	65.005
2005	66.482
2006	65.067
2007	64.785
2008	64.276
2009	63.777
2011	59.788
2012	57.066
2013	55.931
2014	55.088
2015	54.935
2016	55.155
2017	56.026
2018	56.144
2019	57.043
2020	51.436
2021	54.83
2022	56.389
2023	54.451