Year	% (national estimate)
1960	8.55
1971	15.22
1982	19.642
1990	23.02
1994	23.531
1995	31.25
1998	20.81
1999	29.41
2000	28.2
2001	21.24
2002	21.02
2003	23.81
2004	25.13
2005	23.33
2006	22.91
2007	25.64
2008	21.31
2009	21.62
2010	18.97
2011	18.39
2012	17.28
2013	17.03
2014	17.84
2015	17.47
2016	15.71