Year	% of total
1960	92.89940828402369
1961	93.71069182389938
1962	94.91525423728815
1963	96.41693811074919
1964	96.42857142857142
1965	96.12676056338027
1966	94.66292134831461
1967	93.9873417721519
1968	93.8953488372093
1969	94.15384615384616
1970	94.35897435897435
1971	93.93203883495144
1972	93.44978165938865
1973	93.85474860335195
1974	92.56505576208178
1975	92.17391304347827
1976	92.70315091210614
1977	91.82692307692307
1978	90.49079754601227
1979	87.73006134969324
1980	87.80068728522336
1981	87.6
1982	88.17427385892115
1983	88.6319845857418
1984	87.67123287671232
1985	88.74538745387454
1986	88.95027624309392
1987	87.5748502994012
1988	87.3887240356083
1989	87.81869688385268
1990	92.4453781512605
1991	93.59238562091504
1992	93.70005970149255
1993	91.95563775510203
1994	92.99051569506727
1995	93.07969758064516
1996	91.29911161731206
1997	93.605
1998	93.06548500881834
1999	91.77304812834224
2000	92.6845648312611
2001	91.39388415672913
2002	92.90968013468014
2003	89.95697388632871
2004	85.8012125748503
2005	85.34888888888888
2006	85.56333333333333
2007	82.95205766710355
2008	85.2803039073806
2009	87.3931736526946
2010	88.92755351681957
2011	88.32169616519174
2012	88.23549483013294
2013	87.19058823529411
2014	87.80767830045522
2015	90.73205714285713
2016	93.03030683403068