Year	Percent
1980	44.45154
1982	49.28348
1984	53.66914
1991	62.3346
1992	65.54929
1993	67.51616
1994	69.02461
1995	68.12966
1996	69.09601
1997	69.41318
1998	70.08929
2003	77.02777
2005	77.5412
2006	83.71225
2008	83.57412
2009	86.02171
2010	90.09459
2011	91.99573
2012	90.73103
2013	84.02132
2014	79.7484
2015	80.75004
2016	83.29509