Year	Percent
1990	67.11413
1991	67.20852
1992	66.75796
1993	67.58248
1994	67.97797
1995	68.47466
1996	69.1518
1997	70.07428
1998	69.88494
1999	69.6485
2006	72.40645
2007	73.97946
2009	74.44132
2010	76.39973
2011	77.47131
2012	78.26327
2013	78.98496
2014	79.489
2015	80.07839
2016	79.88335
2017	79.35676