Year	% of total
1960	100
1961	100
1962	100
1963	100
1964	80.48780487804878
1965	81.63265306122449
1966	82.6923076923077
1967	75.86206896551725
1968	76.81159420289855
1969	83.48623853211011
1970	88.70967741935483
1971	83.33333333333333
1972	76.7123287671233
1973	51.30434782608696
1974	45.689655172413794
1975	63.54166666666667
1976	87.01298701298703
1977	78.26086956521739
1978	82.22222222222223
1979	60.71428571428571
1980	58.78378378378378
1981	73.38709677419355
1982	72.72727272727273
1983	73.33333333333334
1984	59.375
1985	66.48648648648648
1986	73.43750000000001
1987	64.70588235294117
1988	65.31365313653137
1989	64.2570281124498
1990	57.73574468085106
1991	60.90949152542373
1992	74.53252032520325
1993	74.38028368794326
1994	70.81103448275863
1995	81.10084656084656
1996	81.19785714285715
1997	84.89356164383562
1998	77.76568965517241
1999	62.99717948717949
2000	60.24357142857143
2001	57.805446685878955
2002	70.31702508960574
2003	67.26880794701987
2004	69.16405693950179
2005	62.76432601880878
2006	69.70099236641221
2007	63.9339405204461
2008	84.62307692307692
2009	78.16002577319587
2010	70.57394396551724
2011	64.80717307692308
2012	61.17778333333334
2013	67.37886699507388
2014	65.16253856942497
2015	48.64735294117647
2016	57.75328693790151