Annual % of total
1960 63.1578947368421
1961 70.86280056577085
1962 66.15776081424936
1963 74.68706536856746
1964 76.66666666666666
1965 83.46774193548386
1966 87.72845953002611
1967 82.57345491388044
1968 88.73591989987484
1969 80.61573546180159
1970 76.40984908657666
1971 77.08333333333333
1972 77.61976047904191
1973 76.8956289027654
1974 76.07843137254902
1975 69.22462030375699
1976 73.95209580838323
1977 73.91920623671156
1978 70.9103840682788
1979 74.19122933141625
1980 72.92634372926344
1981 78.21846553966189
1982 73.60838244924688
1983 74.0952380952381
1984 72.09821428571429
1985 64.31693989071039
1986 61.933045356371494
1987 48.047162859248346
1988 41.05075690115761
1989 42.97452752670502
1990 48.83498806682577
1991 49.041674757281555
1992 67.78393939393939
1993 64.11532224532225
1994 61.138300884955754
1995 55.21635446685879
1996 53.52515731874144
1997 53.66464827586207
1998 59.154134007585334
1999 60.03495575221238
2000 60.238114583333335
2001 55.500540540540534
2002 64.24862396204033
2003 54.178491260349595
2004 59.69778306374881
2005 47.525379061371844
2006 53.47857982370224
2007 52.87869771863117
2008 64.25241594022417
2009 50.55942332896461
2010 90.56781400966184
2011 89.75174825174825
2012 53.1543935538592
2013 52.72493009565857
2014 56.83419600938967
2015 52.83489216202
2016 66.253928734582