Year	Percent
1971	61.48074
1972	64.46499
1973	65.06024
1974	62.80742
1975	67.91561
1976	75.07022
1977	74.1925
1978	89.78444
1979	88.33687
1980	86.60273
1981	81.75639
1982	89.7416
1984	86.09865
1985	84.7049
1986	80.70039
1987	69.34656
1988	74.48445
1989	74.08494
1990	73.19074
1991	73.58025
1992	65.9569
1993	64.49726
1994	64.06921
1995	59.16517
1996	50.77778
1998	90.19149
1999	93.95538
2003	99.68061
2005	93.34996
2006	89.69415
2007	102.30838
2008	105.69221
2009	103.93497
2011	100.48105
2013	96.95084
2014	91.63998
2015	91.9767
2016	94.20541