Year	% (national estimate)
1979	8.56
1990	13.5
1991	25.79
1992	14.5
1993	15.6
1994	16.2
1995	16
1996	15.8
1997	16.1
1998	16.9
1999	18.2
2000	19.2
2001	31.78
2002	21
2003	21.2
2004	29.4
2005	26.39
2006	40.51
2007	32
2009	34.92
2010	42.08
2011	40.81
2015	42.01