Year	% (national estimate)
1979	35.75
1990	39.4
1991	61.08
1992	40
1993	41.3
1994	41.7
1995	40.6
1996	39.9
1997	41.1
1998	41.6
1999	42.9
2000	44.4
2001	62.1
2002	48.8
2003	52.9
2004	57.8
2005	55.88
2006	82.09
2007	59.9
2009	63.89
2010	71.25
2011	70.16
2015	70.93