Year	%
1972	37.48034
1973	33.52757
1974	47.31275
1975	53.5105
1976	57.92818
1977	59.69312
1978	62.12013
1979	62.98953
1981	71.0505
1983	84.69751
1984	84.08986
1988	90.78709
1989	90.9993
1990	89.99538
1991	90.91016
1992	91.13759
1993	90.13181
1994	90.01102
1995	89.63865
1996	91.35356
1998	90.83591
1999	97.1128
2000	93.25744
2001	94.47193
2002	94.46948
2003	93.79602
2004	93.74328
2005	92.31375
2006	93.23903
2007	96.5836
2009	98.91325
2010	98.57422
2011	97.7312
2012	98.5156
2013	99.39158
2014	99.00214
2015	98.91984
2017	99.20801