Annual % of total
1960 96.35036496350364
1961 89.43661971830986
1962 90.00000000000001
1963 90.63444108761328
1964 80.94059405940594
1965 86.40776699029125
1966 85.46637744034706
1967 82.94573643410853
1968 79.29292929292929
1969 68.48920863309353
1970 72.86135693215338
1971 61.07784431137725
1972 57.39219712525667
1973 63.096500530222684
1974 67.36183524504693
1975 70.73170731707317
1976 69.01521216973579
1977 73.9770867430442
1978 65.79139314369074
1979 71.28482972136221
1980 74.54831107619796
1981 74.44529456771232
1982 73.9460370994941
1983 73.84615384615384
1984 76.31578947368422
1985 75.82222222222222
1986 76.21359223300969
1987 72.97543221110101
1988 68.51063829787233
1989 61.23348017621145
1990 57.522834507042255
1991 56.943362218370886
1992 50.00454545454546
1993 47.31461636828645
1994 46.20257743362831
1995 60.42616586538462
1996 67.46918719211821
1997 69.97415458937198
1998 76.66202090592334
1999 75.87373115577888
2000 58.3053
2001 64.41650190114069
2002 59.928493317132435
2003 66.49708013172338
2004 64.698025477707
2005 66.60320754716982
2006 59.30945340501792
2007 59.603978405315615
2008 56.13157450076805
2009 53.564109589041095
2010 52.371781914893624
2011 50.73612158054711
2012 59.43728695652174
2013 54.37275862068965
2014 52.66881011403074
2015 49.60601175894169
2016 49.85490976399815