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	93.34181818181818
1991	96.67545454545456
1992	91.67500000000001
1993	91.67500000000001
1994	94.73083333333334
1995	97.78666666666666
1996	95.90615384615384
1997	98.72692307692307
1998	94.29428571428572
1999	96.91357142857143
2000	95.342
2001	97.78666666666666
2002	91.67500000000001
2003	96.25875
2004	88.4394117647059
2005	84.92
2006	86.85
2007	90.71
2008	94.57
2009	98.42999999999999
2010	98.42999999999999
2011	100.84249999999999
2012	99.009
2013	99.009
2014	99.53285714285714
2015	97.78666666666666
2016	81.89633333333333