Year	% (national estimate)
1960	37.950516267290084
1970	52.068851373717315
1976	62.05228758169935
2010	93.36371779335056
2011	94.25038884348722
2012	93.84924016940485
2013	94.45848470489129
2014	94.51272698437872
2015	93.68153467162848