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	91.78082191780823
1974	92.7710843373494
1975	92.4731182795699
1976	92.4731182795699
1977	95.57522123893806
1978	95.37037037037037
1979	96.58119658119658
1980	97.19626168224298
1981	97.22222222222223
1982	96
1983	97.36842105263158
1984	97.47899159663866
1985	97.2972972972973
1986	97.11538461538463
1987	96.9387755102041
1988	97.14285714285712
1989	97.36842105263158
1990	98.6597619047619
1991	98.92372093023256
1992	97.78666666666666
1993	98.05239130434784
1994	98.30680851063829
1995	99.08702127659575
1996	99.53285714285714
1997	97.55603773584906
1998	100.00909090909092
1999	100.384125
2000	59.03609929078014
2001	52.15795031055901
2002	61.29128571428571
2003	61.29128571428571
2004	60.208175675675676
2005	55.56060606060606
2006	57.23624338624339
2007	62.71101449275363
2008	74.56818181818181
2009	71.1485657370518
2010	71.09758992805754
2011	69.2263782051282
2012	73.92954983922829
2013	81.27514754098361
2014	84.97567307692307
2015	83.66351906158359
2016	64.79472850678734