Annual % of total
1960 16.1231884057971
1961 14.147909967845662
1962 14.732142857142858
1963 13.556338028169012
1964 16.545454545454547
1965 18.21247892074199
1966 18.67816091954023
1967 19.56224350205198
1968 19.212410501193318
1969 21.242937853107343
1970 23.800195886385897
1971 22.746419545071607
1972 19.16829109811566
1973 22.106722106722106
1974 27.848101265822777
1975 27.45411013567438
1976 25.703703703703706
1977 29.743589743589745
1978 32.74985883681536
1979 35.37941034316095
1980 44.9645390070922
1981 36.06393606393606
1982 39.438033115905675
1983 40.7015857760692
1984 43.48641049671978
1985 47.27780362959516
1986 46.06281292671825
1987 50.19704433497536
1988 54.85485485485485
1989 45.183673469387756
1990 41.337090909090904
1991 36.045450121654504
1992 35.68776785714285
1993 29.05256038647343
1994 7.882336448598131
1995 8.274256410256411
1996 5.770406091370559
1997 2.973243243243243
1998 3.055833333333333
1999 3.704040404040404
2000 2.19788643533123
2001 2.505403726708075
2002 2.249093333333333
2003 2.0520924574209247
2004 1.9659906759906758
2005 1.8019656019656023
2006 1.8108641975308641
2007 1.7379146919431279
2008 2.462254196642686
2009 8.997731481481482
2010 9.367663755458516
2011 10.62265873015873
2012 13.691200873362448
2013 11.48329853862213
2014 13.41756704980843
2015 4.484299802761341
2016 0.297525354969574