Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0.06944444444444445
1970	0.14738393515106854
1971	0.3750937734433608
1972	5.263157894736842
1973	10.186513629842182
1974	9.66183574879227
1975	22.86527514231499
1976	42.153284671532845
1977	41.4612676056338
1978	36.347673397717294
1979	35.51912568306011
1980	23.52941176470588
1981	12.362637362637363
1982	0.36900369003690037
1983	3.1914893617021276
1984	2.6022304832713754
1985	0.7707129094412332
1986	0.17006802721088435
1987	10.55363321799308
1988	3.0844155844155843
1989	7.2784810126582276
1990	5.448717948717949
1991	3.9942938659058487
1992	4.545454545454546
1993	3.427719821162444
1994	8.665511265164644
1995	31.211498973305957
1996	42.72727272727273
1997	43.5960591133005
1998	53.278688524590166
1999	56.666666666666664
2000	50.947867298578196
2001	76.8166089965398
2002	93.44729344729345
2003	93.90462531373252
2004	93.19929036073329
2005	92.80167264038232
2006	92.00906772456786
2007	90.44048734770385
2008	88.11445341159208
2009	90.19670050761421
2010	90.27863777089783
2011	88.33962264150944
2012	86.6158868335147
2013	76.79826933477555
2014	76.16797900262468
2015	62.65965439519159