Annual % of total
1960 89.33975945488103
1961 89.61421351964283
1962 90.24593900972727
1963 90.48215583075728
1964 90.86472001675193
1965 91.11421493492654
1966 91.26485868739802
1967 91.43384413892046
1968 91.72587447833783
1969 92.1627322655627
1970 92.61986407562019
1971 63.84807632086398
1972 64.5306849429194
1973 65.59531205722847
1974 66.0149132382375
1975 67.22998696838248
1976 68.0231882419223
1977 69.3066788869924
1978 70.57622194755419
1979 70.86884999755726
1980 70.90784397764563
1981 70.63803063825667
1982 71.18742324445559
1983 71.21946246139862
1984 71.55380422006115
1985 71.90964419443061
1986 72.35868748837385
1987 72.91198937604634
1988 73.35384979803503
1989 73.54460576613393
1990 80.897640411538
1991 80.5235572451317
1992 80.06631299153227
1993 79.94570987189518
1994 79.60766534144187
1995 80.07610283510198
1996 80.11500258823872
1997 80.08155144718013
1998 79.93037489132546
1999 80.00964937566644
2000 80.09789142706417
2001 80.36104571358754
2002 80.66006805305149
2003 81.45459440811624
2004 82.15993181526864
2005 82.67257033752115
2006 83.14020914714185
2007 83.46345444617243
2008 83.58534510735086
2009 83.67222636570914
2010 84.15948079694284
2011 84.5959005537557
2012 84.48457586137297
2013 84.2348979743437
2014 84.42221479255407
2015 88.08939589093121