Annual % of total
1960 93.77638048935982
1961 93.60324055808007
1962 94.42113367379139
1963 94.60904531539282
1964 95.20367033281427
1965 95.14102392216938
1966 95.26393589017623
1967 96.50803223565785
1968 96.6425595245175
1969 97.01007706179729
1970 97.00480674457198
1971 96.51399786561029
1972 96.5739067579185
1973 97.34559990980391
1974 96.1724417757311
1975 95.47404891000811
1976 94.9935627986153
1977 95.52269975552451
1978 93.39450471792371
1979 92.610890913916
1980 91.32407255619313
1981 90.7445214476561
1982 88.51455277981916
1983 87.43145522646029
1984 87.10336967688794
1985 84.9682291429023
1986 84.56660030791178
1987 83.47244169794277
1988 84.73903951432817
1989 84.91936201046106
1990 84.55205339107097
1991 83.8847678901191
1992 83.95401953761076
1993 82.42967512253773
1994 82.68251328594704
1995 81.47549791084448
1996 81.2193281130974
1997 80.35858715038619
1998 79.39872965637733
1999 80.61843811737995
2000 80.67376563425594
2001 80.601638342528
2002 81.83018976969308
2003 84.31138173902211
2004 82.70647334241079
2005 81.61186176445815
2006 81.45311669863526
2007 83.48271492333387
2008 83.21545458243469
2009 81.22805604231299
2010 80.91095442176412
2011 89.76594207466343
2012 94.62155285384954
2013 94.63330153072364
2014 94.40746890159542
2015 93.02645510746291