Year	% of total
1960	49.35064935064935
1961	48.52384557153672
1962	55.55555555555556
1963	56.8856660623867
1964	61.66025533812789
1965	60.33269020180424
1966	62.7879916220619
1967	71.63076923076923
1968	72.62364405221548
1969	75.69543792719759
1970	77.45208568207441
1971	75.92060590232437
1972	77.77777777777779
1973	83.50748946575646
1974	77.57453345471097
1975	77.0407020243223
1976	76.75130968535993
1977	80.1789293331142
1978	76.70015705341969
1979	74.02603614992995
1980	69.99586048615708
1981	69.61618264412107
1982	66.4319508427306
1983	65.81954192111877
1984	66.03995591885712
1985	61.66017683723148
1986	60.723524222773214
1987	61.00789468886174
1988	61.80929912382124
1989	63.14784832773708
1990	54.857734222520705
1991	54.817738539355396
1992	55.43669716887916
1993	53.78712034426278
1994	54.96197070944226
1995	54.05219155105384
1996	54.013229748387495
1997	54.32858393084706
1998	54.22360183211005
1999	57.16147771931648
2000	58.02248339294839
2001	59.01984646196172
2002	61.373367758811604
2003	65.15587707450646
2004	62.16009485180307
2005	61.379359197425096
2006	61.18412962686099
2007	64.54050867222418
2008	64.49514181328108
2009	63.05929880032086
2010	61.97064375333314
2011	73.82950186756615
2012	81.1471732826566
2013	81.5973536309712
2014	82.79272981143458
2015	80.25937295342453