Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0.3879310344827586
1965	0.34491907667816396
1966	0.4003313086692435
1967	0.540439806187104
1968	0.4642971501761127
1969	0.6888847514429344
1970	0.7609063239770038
1971	0.700079554494829
1972	0.5318384361075177
1973	0.7088919710278933
1974	0.30881527231892203
1975	0.2829854969932791
1976	2.115445944509408
1977	5.539415068758473
1978	7.835090010260237
1979	12.884221311475407
1980	6.808786576963606
1981	7.186016400517911
1982	7.22719605553393
1983	7.360781039244651
1984	8.386466770061462
1985	10.770818995182383
1986	10.79472804170355
1987	13.357188373118964
1988	15.473554735547356
1989	17.069701280227598
1990	15.002515549412577
1991	16.687947197673118
1992	17.47685048754063
1993	20.17389088533159
1994	23.343554321416175
1995	28.33572765864809
1996	28.655424201715405
1997	24.12685648326279
1998	24.081991397455845
1999	27.60083456876254
2000	36.107895622895626
2001	34.71344532437405
2002	41.50134570220761
2003	44.39294117647059
2004	40.416924101198404
2005	42.76682421072296
2006	43.69048483415125
2007	44.55617296822697
2008	44.08853955160744
2009	41.87159138574864
2010	41.738484478371504
2011	46.008017955458556
2012	43.780951932583214
2013	42.99397614408592
2014	37.74141057004385
2015	37.27372825846426
2016	40.563327064455464