Annual % of total
1960 39.48863636363637
1961 64.3027888446215
1962 76.34245187436677
1963 -28.29131652661065
1964 42.608695652173914
1965 54.83415666901905
1966 32.09764918625678
1967 35.0197628458498
1968 21.59709618874773
1969 18.12206572769953
1970 37.286063569682156
1971 33.303167420814475
1972 35.89857651245551
1973 37.065938353492
1974 32.61583363735863
1975 28.391768292682922
1976 51.277918489523366
1977 47.585581500793474
1978 41.60287081339713
1979 42.46875685156763
1980 33.99004113444468
1981 38.474612279583596
1982 27.940298507462686
1983 12.055780476833108
1984 16.520284399832704
1985 16.431095406360424
1986 16.030373338958025
1987 15.571368773545416
1988 18.373006702103073
1989 13.789186733303044
1990 25.209000708717223
1991 24.59710769230769
1992 40.727367979882644
1993 33.05299117882919
1994 25.150775729646696
1995 24.827484802431613
1996 32.45157142857143
1997 16.59071169208424
1998 18.022914893617024
1999 27.56056298381422
2000 26.838558495821722
2001 22.31570317563189
2002 22.272103620474407
2003 26.95197127937337
2004 20.87227927363807
2005 21.047498729028977
2006 18.681566156615663
2007 23.02882646125963
2008 24.492923368022705
2009 26.4808618127786
2010 24.300764809902738
2011 21.72685640362225
2012 20.258019891500904
2013 22.150422349318085
2014 20.77743613138686
2015 23.647492944496708
2016 31.29924300603401