Annual % of total
1960 76.8327067669173
1961 81.11682586333578
1962 82.16576853990249
1963 82.85591212578073
1964 17.15154146765089
1965 37.18811471166787
1966 32.22407677863551
1967 7.970596713750361
1968 -3.2352941176470593
1969 5.835725023916906
1970 1.1129008639625129
1971 1.2700986353195514
1972 3.715498938428875
1973 6.821963394342761
1974 9.068487952950104
1975 12.181303116147308
1976 23.75942834458118
1977 24.552810902896084
1978 25.161515627728303
1979 24.574512245745122
1980 26.363501263189182
1981 43.717277486910994
1982 49.10791616144119
1983 45.698286102155095
1984 55.50672182006204
1985 55.6966800804829
1986 56.63413621262458
1987 48.17058960615241
1988 49.9331550802139
1989 44.16513386470468
1990 75.68437264957265
1991 37.5829034965035
1992 91.42798348544112
1993 114.09558441558443
1994 116.47478518518517
1995 103.73921301775148
1996 92.06463266545234
1997 103.1821644640235
1998 80.51036851341188
1999 82.22029499199634
2000 66.36671401314395
2001 71.44228059818968
2002 72.72871886120996
2003 67.09759662052849
2004 65.4869860480753
2005 66.80210706319703
2006 65.90810104779675
2007 69.9685365144021
2008 74.62251954464408
2009 82.35601146055437
2010 76.7469124600639
2011 64.36226589452933
2012 76.71351716712526
2013 68.39389397138166
2014 61.90201363962671
2015 58.35794752385279
2016 60.843314419225635