Annual % of total
1960 91.66666666666666
1961 91.11111111111111
1962 79.16666666666667
1963 75
1964 90.38461538461539
1965 89.83050847457626
1966 94.23076923076923
1967 96.73913043478262
1968 97.57009345794391
1969 96.67519181585678
1970 95.24647887323943
1971 79.89690721649484
1972 76.43908969210175
1973 43.54727398205659
1974 40.68594485541359
1975 42.21311475409836
1976 43.99486191393706
1977 51.21951219512195
1978 58.5838991270611
1979 50.1085776330076
1980 51.63073521282476
1981 49.470161740100394
1982 49.384787472035796
1983 48.30564784053156
1984 39.8776758409786
1985 34.184561810795124
1986 41.32841328413284
1987 37.01002734731084
1988 38.917089678511
1989 38.6277001270648
1990 20.510338983050847
1991 20.14742528735632
1992 22.51108459869848
1993 23.016276595744685
1994 15.939887387387389
1995 18.69295010845987
1996 21.52031779661017
1997 21.182049689440994
1998 24.768985801217042
1999 21.986784232365146
2000 22.300385438972164
2001 27.462467248908297
2002 27.35429561200924
2003 26.395717539863323
2004 27.399029345372462
2005 30.254730021598274
2006 35.762326732673266
2007 38.93358024691358
2008 38.80094430992736
2009 36.93192857142857
2010 40.975073375262056
2011 38.81558510638298
2012 39.626243567753
2013 45.22633333333333
2014 45.33745454545454
2015 44.56609489051095
2016 43.09206654991243