Annual % of total
1960 1.4844804318488531
1961 1.1315417256011315
1962 1.1450381679389312
1963 1.1126564673157162
1964 0.2564102564102564
1965 0.5376344086021505
1966 0.7832898172323759
1967 0.4052684903748733
1968 0.7509386733416771
1969 1.0262257696693273
1970 2.3828435266084194
1971 2.514367816091954
1972 4.04191616766467
1973 4.7279214986619085
1974 4.313725490196078
1975 7.673860911270983
1976 9.880239520958083
1977 8.646350106307585
1978 10.170697012802277
1979 10.567936736161036
1980 11.81154611811546
1981 14.369310793237974
1982 16.895874263261295
1983 17.142857142857146
1984 20.200892857142854
1985 26.721311475409838
1986 30.6695464362851
1987 43.10980103168755
1988 51.20213713268033
1989 48.15119145439606
1990 41.571002386634845
1991 39.87417475728156
1992 37.695734265734266
1993 41.47293139293139
1994 44.13380530973451
1995 40.210187319884724
1996 41.4355950752394
1997 45.11674482758621
1998 39.868773704171936
1999 32.978661504424785
2000 28.57204166666667
2001 26.155922444183314
2002 27.317627520759196
2003 28.13503219871205
2004 49.12593720266413
2005 49.27944945848375
2006 60.15891283055828
2007 58.665028517110265
2008 45.48358655043586
2009 71.12922673656618
2010 50.044806763285024
2011 64.10839160839161
2012 30.356166242578457
2013 30.949587932303164
2014 28.36329812206573
2015 57.117238295633875
2016 36.938031064412975