Year	Percent
1984	73.43099
1985	72.9866
1986	72.95854
1987	73.11717
1989	68.48253
1990	70.15502
1991	66.84857
1992	66.6083
1993	71.17484
1994	67.4637
1995	68.13537
1996	67.93386
1997	76.84497
1998	76.9125
1999	80.11328
2000	77.67131
2001	82.35321
2002	80.94438
2003	81.46817
2004	82.29112
2005	82.16893
2006	78.92891
2007	82.23602
2008	81.16854
2009	82.28945
2010	81.07463
2011	79.80378
2012	76.94044
2013	78.78072
2014	79.06327
2015	78.03482
2016	76.76961
2017	74.92127