Year	% of total
1960	83.60197368421053
1961	82.57800367076096
1962	80.51777618706751
1963	77.89855072463769
1964	74.99358371118144
1965	73.27210830496398
1966	71.30611324159712
1967	68.3927147035363
1968	66.06911846239142
1969	62.02419755814596
1970	54.137724550898206
1971	50.025662959794694
1972	49.620393460792464
1973	48.76658319569503
1974	46.53939175629084
1975	47.11905239911665
1976	43.41240784392397
1977	41.66626442052421
1978	41.66478987432999
1979	44.220523511697934
1980	47.238654110075245
1981	46.25741670470105
1982	43.42731600146466
1983	43.225256665178755
1984	44.84784889821616
1985	45.93742321238431
1986	44.835737179487175
1987	45.62407459282084
1988	43.463283481767775
1989	44.51255601589584
1990	48.848467917346376
1991	50.85999488141956
1992	54.88859785960457
1993	57.965870307167236
1994	55.066664798206276
1995	54.471947339550184
1996	54.49883944787505
1997	57.31018737118231
1998	56.849735125518876
1999	57.347575620767486
2000	58.08974844218786
2001	61.9054395842356
2002	59.86715791886317
2003	59.48825015660889
2004	59.85495337007206
2005	55.89341269841269
2006	55.15102103328569
2007	57.785564424173316
2008	59.201197281631025
2009	57.740102397021175
2010	59.55502341137123
2011	64.51025971411315
2012	60.78345079787234
2013	58.255755901557
2014	59.22079090693819
2015	57.97125755202506
2016	53.52027791087686