Annual % of total
1964 71.22950819672131
1965 65.33052039381153
1966 82.59551243177683
1967 78.89273356401385
1968 77.71395749569213
1969 76.96903856599674
1970 80.32345013477088
1971 80.20134228187919
1972 76.59384752563531
1973 77.4792572105887
1974 75.10121457489879
1975 70.60379021595415
1976 82.32118758434548
1977 79.17981072555204
1978 79.48717948717949
1979 81.9557625145518
1980 80.09893455098934
1981 76.52545666537117
1982 80.27465667915106
1983 79.74062390466176
1984 78.30746489283075
1985 78.49231868524473
1986 82.7094972067039
1987 85.37054860442733
1988 83.30676383511728
1989 84.16402356139557
1990 81.23747126436783
1991 69.85334426229508
1992 73.22087709799675
1993 73.57616510538641
1994 84.98892857142857
1995 68.60227390180879
1996 70.69956258411844
1997 68.69990600144614
1998 69.22211798152097
1999 67.05835018963337
2000 73.95562773722628
2001 68.69689208633093
2002 73.10512409927942
2003 80.47227897838899
2004 76.00486182190379
2005 80.7019124643197
2006 83.33751780264495
2007 80.0653381147541
2008 78.45450000000001
2009 46.227858064516134
2010 57.52816513761467
2011 50.99970409051349
2012 28.403352601156072
2013 57.17078478964402
2014 63.682057613168716
2015 64.85266935483871
2016 64.33099181073703