Year	% of total
1960	71.01190476190476
1961	71.16082224909312
1962	73.02716688227684
1963	76.0810810810811
1964	66.96950032446463
1965	63.36853807670928
1966	70.90039147455414
1967	72.24152910512598
1968	72.15702144880616
1969	69.85365853658537
1970	45.39041595718803
1971	40.836770771950505
1972	25.624110723062994
1973	24.4927258805513
1974	30.134467302608897
1975	35.283342873497425
1976	28.196966860138552
1977	33.13200280112045
1978	21.07084212995543
1979	33.69504059159232
1980	28.0154355016538
1981	39.126658243840815
1982	47.51143897656177
1983	41.87861473068079
1984	32.04744713769985
1985	30.94362436394781
1986	29.86394884861304
1987	29.851787271142115
1988	32.52959419910017
1989	31.448989875853222
1990	34.206968625718076
1991	38.97077681505826
1992	43.382117593712216
1993	38.13240778549068
1994	42.59460097833683
1995	37.101707049965775
1996	38.41081081081081
1997	41.25186187010847
1998	44.428061443520264
1999	28.639865875677067
2000	39.30628324214277
2001	38.092268289420886
2002	36.71104340256186
2003	38.1308516221374
2004	38.69162327718224
2005	34.922828407686254
2006	37.61266346666667
2007	38.15474830879427
2008	35.957687277622846
2009	39.840457568502266
2010	40.128272052324554
2011	39.749112916878275
2012	38.36103600758054
2013	39.997990916788545
2014	38.109748577191844
2015	38.06424881825032
2016	37.33509940704569