Year	% 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