Year	% of total
1960	99.95162066943129
1961	99.98308710647689
1963	99.98510901018722
1964	99.99456254994715
1965	99.9904575978221
1969	99.88153351781928
1970	99.86440028410439
1971	99.97543828236411
1973	99.72083044438659
1974	98.80795597198704
1975	98.24400955562314
1976	98.21283959471853
1977	98.05011990570107
1978	97.9066511001891
1979	98.29367605158372
1980	97.9878819471358
1981	98.1149035043203
1982	97.56313364912734
1983	97.54972433412874
1984	97.87650030532872
1985	97.45564326795315
1986	97.78462118308767
1987	97.8630531407606
1988	97.1510296747327
1989	97.12597863753246
1990	98.04491405834317
1991	96.54590190406438
1992	96.88957220435566
1993	97.60032632887082
1994	97.83544978272283
1995	95.46345923007998
1996	95.16427457133938
1997	95.50036081379989
1998	95.01434889097776
1999	94.15364098534754
2000	93.84683252832015
2001	94.19989598858078
2002	93.9850559778198
2003	94.33435194990038
2004	94.0176796319096
2005	93.05623663211986
2006	92.75138984317827
2007	92.72577938051417
2008	92.32417382701232
2009	92.88726258193482
2010	93.6745002289704
2011	92.18561000035038
2012	91.23393805581993
2013	91.55436790140136
2014	90.92188385709487
2015	93.46100460960555