Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0.03666734569158688
1966	0.08889064475347662
1967	0.09289881461112556
1968	0.040917986123465575
1969	0.10506010816024251
1970	0.09241534094659713
1971	0.13526918567950222
1972	2.0445759423890135
1973	2.7043300025621315
1974	2.734655838104114
1975	14.858724798887676
1976	18.512130752847487
1977	22.128260120681418
1978	25.60290254511003
1979	22.130940609681694
1980	27.501142074006395
1981	36.63633004686619
1982	39.236473993086264
1983	37.6636140682839
1984	41.31323620079826
1985	42.88957733687811
1986	50.65829495089945
1987	46.16138158751036
1988	47.66789571617882
1989	45.90318788659072
1990	46.70717338886453
1991	52.22902633190447
1992	43.54237473961188
1993	42.26937561533112
1994	51.265592151366505
1995	47.16001429602206
1996	52.816315501290646
1997	46.866747986005926
1998	46.33952805889503
1999	47.26746664255545
2000	39.46540339183783
2001	44.62328661159071
2002	46.42876618950238
2003	49.79723590808028
2004	51.08753700394929
2005	45.70264894389543
2006	46.743575785491956
2007	44.999092882148595
2008	42.62278676931698
2009	38.19287868583643
2010	38.95190623737034
2011	40.24851251880149
2012	38.475450022831595
2013	43.427148747639365
2014	42.25028328796384
2015	34.73640007163545