Annual % of total
1960 0
1961 7.4365175332527205
1962 12.160413971539457
1963 11.14864864864865
1964 21.090201168072685
1965 26.959421901056142
1966 21.966072205306652
1967 21.242397914856646
1968 20.801295022258195
1969 21.98373983739837
1970 0.9000243249817562
1971 3.6142211746218815
1972 11.072306299314448
1973 8.22166921898928
1974 7.688771405585565
1975 13.932455638236977
1976 15.493353304624602
1977 8.61344537815126
1978 38.18320431620924
1979 17.916566192428263
1980 38.33517089305402
1981 24.060328490208466
1982 18.274348678681484
1983 31.586649014005992
1984 42.944816915936045
1985 38.087561086200814
1986 43.41137445315129
1987 47.72885789014821
1988 46.46398462412091
1989 45.85184845847267
1990 57.357302990131096
1991 57.453683896026284
1992 48.3039676541717
1993 49.17283789301756
1994 52.29639133473095
1995 64.69581930184806
1996 70.87
1997 53.60274886722504
1998 73.3645975315267
1999 65.72603301521795
2000 50.56997836874921
2001 54.91917346529357
2002 55.57732744683497
2003 52.55566793893129
2004 48.58375427023207
2005 68.84020901224856
2006 52.63660693333334
2007 50.853541583764425
2008 49.61152322338687
2009 48.71773876030859
2010 47.20687201697013
2011 48.05216438124259
2012 50.670272425773845
2013 50.422308521283966
2014 53.23371298897774
2015 54.00641638692883
2016 54.929536798046726