Year	% (national estimate)
1960	40.01
1992	48.58
1993	54.76
1994	51.81
1995	56.05
1996	53.81
1997	44.44
1998	41.64
2000	35.9
2001	40.16
2002	34.2
2003	27.96
2004	29.97
2005	32.8
2006	37.02
2007	43.53
2008	44.96
2009	50.5
2010	50.13
2011	50.5
2012	49.62
2013	48.4
2014	48.1
2015	46.06
2016	47.53