Annual % 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