Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0.019217464832039358
1970	0.005328312878532228
1971	0.18186246650970206
1972	0.2841787528528308
1973	1.0058154903515728
1974	0.5532244367850542
1975	0.7357061073351361
1976	1.7569611742954787
1977	0.9904087863716299
1978	0.8536138694448966
1979	1.4612761811982464
1980	2.6669474300990608
1981	3.327393723408124
1982	3.4007012845135938
1983	3.0222399417566606
1984	1.7475826799654548
1985	2.001321477188597
1986	1.6517453286333719
1987	1.1281540805091776
1988	0.9849621889972869
1989	0.9497282608695652
1990	0.9979762707829054
1991	0.879488720444074
1992	1.0918953414167198
1993	0.7694336685130502
1994	2.0068115996072144
1995	2.264547452837025
1996	3.9033253540218618
1997	9.608399816016114
1998	8.382973442541573
1999	9.258782434644889
2000	9.133581687571574
2001	10.022010838085185
2002	13.498835013775597
2003	15.29965450637939
2004	20.046845856888797
2005	27.297414016479816
2006	30.641243377472243
2007	31.407140892992626
2008	38.84454848896063
2009	36.9158766432886
2010	31.795052292839905
2011	29.330470306963534
2012	24.939613937443443
2013	20.443070582174137
2014	17.19337040687546
2015	18.89831240640479