Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0.08328623694934412
1969	0.8480508292052552
1970	0.9006804053061824
1971	0.9019241047568145
1972	0.6579080139654094
1973	2.105383168335645
1974	5.984185825678859
1975	6.14655903276936
1976	6.660130381684641
1977	6.365164876642762
1978	6.591337099811676
1979	5.412323157110946
1980	6.480881399870382
1981	5.710895664527813
1982	6.461400716275369
1983	6.016764459346186
1984	5.911306508649527
1985	6.194099798242966
1986	6.2777331070014
1987	5.197386690831494
1988	5.279338035655284
1989	5.501711156741957
1990	4.866051578479324
1991	4.475424822542482
1992	4.918648148387848
1993	5.116707059448671
1994	4.967007650218489
1995	4.950287678490026
1996	4.869882818444681
1997	2.7830750205147763
1998	4.1859188937057565
1999	4.418819188191882
2000	4.3801809641753415
2001	4.245006032264608
2002	4.078932288682135
2003	4.150054741886839
2004	3.776157448574308
2005	4.000160126499934
2006	3.509961247761375
2007	3.993724147767794
2008	3.8762645046117226
2009	3.736443517956566
2010	3.3277437746289933
2011	3.6336354781815148
2012	3.790005614823133
2013	2.8416686325391205
2014	3.955791061517337
2015	3.5086762969019714