Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0
1970	0
1971	0
1972	0
1973	0.05780135672032094
1974	0.02188298729036098
1975	0.021135125310157963
1976	0.03944835421466217
1977	0.056671030336002536
1978	0.10757083539510769
1979	0.15375679092493252
1980	0.15719672821209682
1981	0.15440928110071758
1982	1.709307188006511
1983	1.795433534290811
1984	1.8798213750021373
1985	1.9042164149452498
1986	2.056909212283044
1987	2.0772470550945217
1988	2.136913792296845
1989	2.1479554231212634
1990	1.2964196035330644
1991	1.2873349901379794
1992	1.2807844873832759
1993	1.2439370514676358
1994	1.2534478795540742
1995	1.399556118769735
1996	1.4290522605481288
1997	1.4432451520781195
1998	1.3135469012724896
1999	1.3237597886778603
2000	1.2823364200821254
2001	1.2889094618329373
2002	1.3314380391765361
2003	1.4630242927713741
2004	1.5164756356638454
2005	1.636052117783002
2006	1.706235851034561
2007	1.7851646660510927
2008	1.8466467659161354
2009	1.9482032893129622
2010	3.3206030538636426
2011	3.7192163389001975
2012	4.050227515350661
2013	4.83434239522823
2014	6.300469634982352
2015	7.755687910160288