Year	% of total
1960	93.75287612951179
1961	93.57544680872911
1962	93.67088811744705
1963	93.93110247042964
1964	94.11113865719096
1965	93.95495435238006
1966	93.43431899975701
1967	93.5098963821609
1968	93.54896715353127
1969	93.81762985408437
1970	93.61227862848168
1971	93.87001841706923
1972	93.3399710147222
1973	93.78255538270167
1974	93.4444027586626
1975	92.72491955411434
1976	92.99609428097628
1977	91.90301841129364
1978	91.78857577247676
1979	91.74826756951178
1980	91.03050454394989
1981	89.21201412370672
1982	88.49034299509326
1983	87.27272345167712
1984	85.53891722123461
1985	84.2539331970632
1986	83.75479212233819
1987	83.46446323910155
1988	82.50451942264515
1989	82.06105400737948
1990	86.71457386734792
1991	86.4030784273993
1992	85.50897922036373
1993	84.61249467018274
1994	84.10059851507185
1995	83.7905108510317
1996	83.36162729876055
1997	82.84719651662536
1998	82.84127008555234
1999	82.5001139825607
2000	82.34366636238974
2001	82.13178802752287
2002	82.09195171815763
2003	82.27396695092662
2004	81.96154279812625
2005	81.77460714079608
2006	81.71437698470777
2007	81.61764450813031
2008	81.35234459358956
2009	80.26148449726824
2010	80.14902806270184
2011	80.21061627910724
2012	79.76864035028554
2013	78.80862160872547
2014	78.37981505963852
2015	71.5704915402549