Annual % of total
1964 84.00447427293065
1965 82.30337078651685
1966 81.04712041884817
1967 76.81713848508033
1968 72.81475541299119
1969 67.58147512864494
1970 64.68871595330738
1971 57.350096711798834
1972 57.529305680793506
1973 49.04153354632588
1974 47.29493891797557
1975 45.55256064690027
1976 44.62659380692167
1977 42.507345739471106
1978 40.40084388185654
1979 37.23296032553408
1980 38.3177570093458
1981 33.66013071895425
1982 38.4375
1983 30.94170403587444
1984 40.05201560468141
1985 40.21304926764314
1986 42.38578680203046
1987 37.99185888738128
1988 43.99066511085181
1989 33.66197183098591
1990 30.379890510948904
1991 29.157743055555557
1992 30.622666666666664
1993 35.0693253968254
1994 39.24032710280374
1995 15.494366197183096
1996 23.960511363636364
1997 21.23
1998 21.29225806451613
1999 15.834772727272728
2000 16.00513812154696
2001 16.43136612021858
2002 15.852135416666666
2003 15.440000000000001
2004 11.29644549763033
2005 13.771266375545851
2006 6.055596330275229
2007 14.816161616161615
2008 14.466146788990827
2009 16.479230769230767
2010 14.445757575757575
2011 8.748071895424836
2012 8.665796019900498
2013 10.810731132075471
2014 10.08425
2015 9.547218934911243
2016 15.28463327370304