Year	% (national estimate)
1970	75.34
1980	75.7
1983	69.08
1986	65.25
1987	67.63
1988	67.51
1989	74.64
1990	67.9
1991	60.66
1992	65.42
1994	68.69
1995	68.06
1996	68.32
1997	65.88
2003	59.89
2004	62.78
2011	56.58
2012	52.06
2013	53.21
2014	47.09
2015	46.143
2016	44.536
2017	43.065
2018	47.862
2019	46.805