Annual % of total
1960 85.90669210510141
1961 86.25191180816242
1962 87.06993431775336
1963 87.12821768904526
1964 87.97580658701722
1965 88.04199102012956
1966 89.24176866837296
1967 89.50084988008544
1968 90.10461479015234
1969 90.26962042823561
1970 91.53110974448676
1971 91.17777518588038
1972 91.30558851050577
1973 92.09782489114325
1974 91.82731595665142
1975 91.78090792960361
1976 91.88762257738466
1977 92.67901978303821
1978 92.65498939990758
1979 92.82094106708088
1980 93.18251205126165
1981 92.77557890068321
1982 92.9254455862167
1983 92.84942864135523
1984 93.20671425519726
1985 92.87885472992308
1986 93.4217424604167
1987 93.73860918426544
1988 93.57842828188258
1989 93.85217111440396
1990 93.91128568601698
1991 93.68871803625748
1992 94.34266007380121
1993 93.75834560953615
1994 93.88648311648664
1995 93.83177016576778
1996 93.64822076296562
1997 93.51265088985517
1998 93.87865070879005
1999 93.92791207166783
2000 89.32816819002298
2001 98.0530884338196
2002 95.89021478723635
2003 93.88602451318003
2004 94.06821267120928
2005 94.21585218232413
2006 94.28316544661021
2007 94.29310395131101
2008 94.35148822698058
2009 95.51005853499287
2010 94.42474221531253
2011 94.42165586113602
2012 94.37700611510014
2013 93.70804882449004
2014 93.386835655426
2015 89.62563011023737