Year	Percent
1997	72.07963
1998	72.72682
1999	73.00831
2000	73.12829
2001	74.27734
2002	75.15606
2003	74.90448
2004	74.4561
2005	74.32823
2006	74.00438
2007	74.25127
2008	74.70599
2009	76.37591
2010	76.03798
2011	75.57396
2012	75.74347
2013	75.32572
2014	75.35475
2015	76.34007
2016	77.02153