Year	% (national estimate)
1960	95.01
1970	84.73
1980	80.34
2000	60.96
2001	59.43
2002	59.43
2003	59.01
2004	56.43
2005	57.12
2006	56.86
2007	58.71
2008	56.61
2009	55.85
2010	54.83
2011	57.92
2012	57.92
2013	57.43
2014	56.88
2015	54.57