Year	% of total
1960	0.8695652173913043
1961	0.8536025699862322
1962	1.15334329473291
1963	1.1932441324851941
1964	1.452513966480447
1965	2.081021087680355
1966	2.4611261944219174
1967	3.1217481789802286
1968	4.524592298427786
1969	5.758842115992254
1970	6.038647342995169
1971	9.348641801096822
1972	11.198594686157032
1973	7.072819621370563
1974	6.104792194490863
1975	4.055468949952303
1976	6.101751274661938
1977	4.3582479843103075
1978	3.850887573964497
1979	3.0045089629385244
1980	1.0212765957446808
1981	0.5633368059574796
1982	0.6322846042507808
1983	0.6724782067247821
1984	0.5226515992331753
1985	0.4501503502169725
1986	0.5252825383350136
1987	0.5204524194234204
1988	0.4825898991253058
1989	0.5544289196078067
1990	0.7019202793133548
1991	1.0618099992968146
1992	1.2656057072300728
1993	0.42885310548800526
1994	0.46774686640171204
1995	0.586364220537206
1996	0.5493235675810209
1997	0.4774809652858434
1998	1.0850025680534154
1999	0.4776258500429572
2000	0.3432944165507229
2001	0.3461960651861859
2002	0.3452226380508669
2003	0.3746177370030581
2004	0.31629217881468724
2005	0.3703126892661233
2006	0.3218745976567529
2007	0.2633995093243426
2008	0.1864669729697476
2009	0.15448532389423006
2010	0.10294919154605464
2011	0.08268668108383158
2012	0.07484590548869974
2013	0.06693830034924331
2014	0.05991269863912584
2015	0.06808175862747175