Year	% (national estimate)
1979	38.41
1989	49.42
1991	69.4
1992	68.8
1993	71.7
1994	73.77
1995	70.6
1996	72.9
1997	72.8
1998	70.62
1999	75.6
2001	76.2
2002	74.5
2008	70.9
2009	67.07
2011	64.7
2012	67.82