Annual % of total
1960 98.31103862238947
1961 98.19956636876674
1962 98.12457970401019
1963 97.68107568590624
1964 98.19371148817707
1965 98.27097545829727
1966 96.82702205897952
1967 97.11396216919171
1968 97.90572894114278
1969 97.28685525930243
1970 91.15887768629977
1971 92.20331017636022
1972 93.2623520389979
1973 94.53948002861384
1974 94.18104388101524
1975 94.6878129986745
1976 95.2060267756014
1977 95.47634486343203
1978 95.01070221698214
1979 94.94150677877221
1980 94.68905639416842
1981 94.74596442976254
1982 94.56292028812162
1983 94.8361202552001
1984 94.39760852388007
1985 95.70018890031871
1986 94.97225998619818
1987 95.58043796109243
1988 96.17815002680695
1989 96.63051869327862
1990 94.5633807165641
1991 94.05584414124482
1992 94.32196258207462
1993 94.16119400965019
1994 94.27011350365554
1995 93.85006003955132
1996 93.46299998953175
1997 93.5109472268787
1998 94.08694814506546
1999 94.1798350397627
2000 94.59119325030727
2001 94.387342657927
2002 94.07165971727615
2003 93.98922591951074
2004 93.77944440137203
2005 93.41073803058507
2006 92.8859917071343
2007 93.02602135451424
2008 92.78015423089391
2009 92.37083310567317
2010 90.38560275532956
2011 90.85296403667564
2012 90.14823362840765
2013 88.00125275958955
2014 86.04931717838214
2015 82.57463513368832