Year	%
1971	64.44444
1972	68.34549
1973	70.54816
1974	72.54687
1975	78.5528
1976	81.41133
1977	90.00865
1978	89.39225
1979	93.54526
1981	96.9965
1982	97.36622
1983	96.79113
1984	98.03784
1985	97.47993
1986	98.00221
1988	98.13134
1991	97.16853
2004	100
2005	98.51919
2006	94.10827
2010	96.94628
2011	96.7397
2012	98.02278
2013	97.70018
2014	99.11048
2015	97.24594
2016	98.83023