Year	% of total
1960	58.797524314765695
1961	69.91439054219323
1962	75.72744014732965
1963	77.4914089347079
1964	76.82530298551582
1965	74.50555405039285
1966	78.72659176029963
1967	81.75366300366301
1968	84.14558914250463
1969	88.92687559354226
1970	86.15092384734933
1971	92.60786802030458
1972	90.10015967484395
1973	91.23571039738705
1974	89.69990826890316
1975	93.07272969020077
1976	92.85026480500721
1977	91.69715109189669
1978	92.76383993365125
1979	92.23684210526316
1980	92.0689002460723
1981	91.81308766264603
1982	92.38366571699905
1983	92.7299703264095
1984	93.87682449270203
1985	92.90520398603186
1986	92.53270496465427
1987	94.60764906168343
1988	93.23768902675455
1989	94.88695138170533
1990	79.32391594630684
1991	80.62290689886136
1992	80.97591888466414
1993	83.55935352034182
1994	83.05205609698122
1995	84.40127243808226
1996	84.40803382663847
1997	85.43349078165473
1998	86.28221093974518
1999	87.10774178727314
2000	87.51742491445951
2001	86.92757388762585
2002	86.05643440808277
2003	87.26519448131612
2004	88.57426135236962
2005	83.1304144228518
2006	82.9879038206225
2007	82.16684023413653
2008	78.82171994115286
2009	75.9031404249231
2010	79.03534923339012
2011	72.1948166691209
2012	71.46752146199476
2013	68.82111436950147
2014	65.29370737755734
2015	62.80650556959323