Year	% of total
1960	100
1961	100
1962	100
1963	100
1964	100
1965	100
1966	100
1967	100
1968	100
1969	100
1970	100
1971	100
1972	100
1973	100
1974	100
1975	100
1976	100
1977	100
1978	100
1979	100
1980	100
1981	100
1982	100
1983	100
1984	100
1985	100
1986	100
1987	100
1988	100
1989	100
1990	96.67545454545456
1991	91.67500000000001
1992	73.33999999999999
1993	80.674
1994	89.383125
1995	88.4394117647059
1996	81.06000000000002
1997	84.341
1998	76.52869565217391
1999	88.34136363636364
2000	90.80190476190477
2001	84.50043478260869
2002	85.56333333333333
2003	86.5412
2004	89.28347826086956
2005	86.5412
2006	88.85423076923077
2007	85.12678571428572
2008	87.24931034482758
2009	31.237407407407407
2010	89.77827586206898
2011	87.24931034482758
2012	64.60904761904762
2013	95.1128125
2014	93.87519999999999
2015	96.42851851851853
2016	95.60392857142857