Year	Percent
1972	68.7036
1973	70.37508
1974	74.07526
1975	75.50923
1976	75.91339
1977	78.06389
1978	82.8482
1979	81.91848
1980	82.56477
1981	83.23158
1982	85.13038
1983	87.15771
1984	92.32984
1986	90.30682
1998	64.14013
1999	61.77967
2000	59.23942
2002	58.63101
2004	69.2344
2005	80.27541
2006	81.55076
2007	85.18871
2008	88.90993
2009	83.07879
2010	95.39658
2012	86.06678
2013	78.65162