Year	Percent
1992	66.37
1999	72.72
2000	73.97
2001	72.8
2002	74.39
2006	75.77
2007	74.87
2008	75.94
2009	75.51
2012	70.65
2013	71.78
2014	71.71
2015	71.16
2016	70.54