Year	Percent
1991	68.13098
1992	67.8643
1993	68.47887
1994	69.63356
1995	66.33305
1996	66.58902
1997	65.02714
1998	64.20964
1999	61.47324
2000	60.90518
2009	49.76408
2010	49.33144
2011	48.98061
2012	49.76463
2013	50.55933
2014	51.71802
2015	52.28942
2016	52.45328
2017	52.77243