Year	% of total
1971	0
1972	0.0003576934477853163
1973	0.025208928853842558
1974	0.050150935267063684
1975	0.017523315818779306
1976	0.03850538759782838
1977	0.009148803789740572
1978	0.0013846847321360184
1979	0.1449121930910566
1980	0.28528966587763094
1981	0.3179046277067157
1982	0.3439800534254728
1983	0.34047425730276665
1984	0.4582542150998749
1985	0.6180425034938996
1986	0.5373815319288241
1987	0.5338059304086828
1988	0.4858041385236472
1989	0.5355026356711723
1990	4.956219372253069
1991	4.901148939411223
1992	4.838782223617042
1993	4.7615448308858035
1994	4.432576691438496
1995	4.308222122416743
1996	4.623188477735669
1997	4.623782136154348
1998	4.444643312577841
1999	4.905875005463663
2000	5.090048797005534
2001	5.30610374361716
2002	5.3432506576956875
2003	5.49424491906529
2004	5.035095303059731
2005	4.786233153567516
2006	4.599983756945214
2007	4.3587700234367475
2008	4.42196944810057
2009	4.253540576952678
2010	4.029700792147371
2011	3.9494593047711426
2012	3.95856676201122
2013	3.8280779561545213
2014	4.025298513478472
2015	0.16579797919167874