Year	% of total
1960	73.55912446574277
1961	69.2935791166646
1962	67.09916589434661
1963	63.671502997030984
1964	63.89223964616003
1965	71.81951308804686
1966	72.43167424661027
1967	72.065649867374
1968	70.31736644983243
1969	62.87355878610265
1970	70.21939328277357
1971	57.50301397064038
1972	57.99481417458946
1973	60.64820804761288
1974	66.41820086813351
1975	67.19434345747574
1976	57.46971349830625
1977	65.67456065152165
1978	65.02640868434322
1979	68.65935268801154
1980	69.05048076923077
1981	73.01756379302182
1982	73.15259855570024
1983	72.92004193271706
1984	69.2916976693949
1985	70.73064788989987
1986	70.7574413898174
1987	72.51449042022219
1988	74.36499200398762
1989	71.7872037432611
1990	63.91796494644596
1991	62.65917379087702
1992	69.78113298223832
1993	71.45276517879738
1994	68.5229606033275
1995	67.17713581499873
1996	63.86680106021577
1997	64.83792762862531
1998	66.46932570202111
1999	67.9267641364577
2000	69.87340080836422
2001	66.24690913259207
2002	66.26527855566171
2003	57.171626762139184
2004	59.34332020404211
2005	57.52322173461317
2006	57.245608965096494
2007	58.79254264180881
2008	59.39964976987091
2009	61.6683756559503
2010	56.470986545765015
2011	54.989401336073996
2012	63.75345655654199
2013	65.13245546088304
2014	66.5573876915087
2015	59.99708563379369