Annual % of total
1960 55.113024757804084
1961 59.71479500891266
1962 55.96491228070175
1963 45.92186429061
1964 44.45564516129032
1965 36.19077306733167
1966 40.11363636363636
1967 51.670951156812336
1968 53.17855168601437
1969 30.971843778383285
1970 25.51923731699012
1971 19.856866977166877
1972 16.995662565282817
1973 17.32248520710059
1974 15.51774886678048
1975 20.31721470019342
1976 20.4566573742201
1977 17.476432197244378
1978 18.936977980258163
1979 19.527337228714526
1980 30.95340578930378
1981 37.86623672652472
1982 44.404695360536614
1983 49.177017683411854
1984 54.237109601306166
1985 50.83420776495278
1986 51.908206535295584
1987 45.387134647469566
1988 46.96003731923496
1989 76.81873163988249
1990 43.92293146647015
1991 41.299241762604204
1992 40.66380439814815
1993 39.13754649922995
1994 29.243106916677014
1995 27.293381162619575
1996 29.309080064234916
1997 35.09416447210917
1998 33.416398747390396
1999 36.09043128850791
2000 41.495380570527146
2001 43.72838285378744
2002 43.670984786900476
2003 38.60108818222824
2004 34.832983188536616
2005 40.45843864282811
2006 34.71320607375271
2007 30.270143126594917
2008 36.62993663279799
2009 36.73915140086207
2010 65.47492560343878
2011 68.68486041727887
2012 56.243359157727454
2013 56.237048410404626
2014 57.36551290877796
2015 50.12075265834489
2016 56.87536616860358