Year	% of total population ages 15+ (national estimate)
1960	42.24
1970	39.62
1976	44.94
1977	44.32
1978	44.43
1979	44
1980	39.58
1981	43.34
1982	42.91
1983	41.59
1984	41.39
1985	42.27
1986	41.79
1987	43.08
1988	45.14
1990	44.59
1991	45.64
1992	45.57
1993	47.16
1995	46.1
1996	46.88
1997	47.81
1998	47.55
1999	47.36
2000	45.94
2002	46.24
2003	46.71
2004	46.64
2005	47.7
2006	47.2
2007	46.03
2008	44.87
2009	43.2
2010	41.9
2011	40.5
2012	41.6
2015	40.02