Year	% (national estimate)
1970	64.41
1980	67.31
1983	63.53
1986	60.51
1987	61.28
1988	62.77
1989	66.51
1990	65.07
1991	60.62
1992	62.14
1994	62.89
1995	64.65
1996	64.35
1997	61.86
2003	57.06
2004	57.66
2011	52.96
2012	47.17
2013	47.2
2014	46.32
2015	42.403
2016	43.768
2017	41.369
2018	44.204
2019	44.401