Year	Percent
1991	72.82834
1992	72.99249
1993	71.33935
1994	84.20215
1995	72.01841
1996	73.34155
1997	73.48501
1998	72.70023
1999	72.05235
2000	71.46934
2001	65.91528
2002	69.79162
2003	65.43586
2004	66.96672
2005	65.26534
2006	65.27029
2007	65.96321
2008	66.55035
2009	67.31325
2010	67.87663
2011	68.19036
2012	74.48748
2013	75.16396
2014	75.22691
2016	77.77121
2017	78.59421