Year	% (national estimate)
1960	33.91943022479412
1970	47.89792930349299
1979	68.52075081797831
1989	84.33734939759036
1991	86.53670770633835
1999	92.60674157303372
2006	91.34637514384349
2007	93.30346616364066
2008	92.37278444825614
2009	91.61928587673414
2011	92.00474495848162
2012	93.48729792147806
2013	94.16919841084366
2014	94.22806194274989
2015	95.69841645001182