Year	% of total
1971	0
1972	0
1973	0
1974	0.5760873662638779
1975	1.3057847225270738
1976	1.2169603611512545
1977	0.7009301811677735
1978	1.134561875074514
1979	0.9518892579225416
1980	0.7644981942540339
1981	0.8897606492113604
1982	0.5547383090853955
1983	0.9612163158449911
1984	1.6385720632649134
1985	2.232650570500569
1986	1.332614973150567
1987	1.607663859857398
1988	1.324666917818813
1989	1.4358034800938575
1990	2.4396478761775815
1991	2.4867396964145314
1992	2.316364675443368
1993	2.2571600549368505
1994	2.0329717471330038
1995	2.773005078694464
1996	2.6044635828668237
1997	2.9835061026184166
1998	2.6270528919046776
1999	2.6619166856441976
2000	2.4486081265597783
2001	3.674117604483111
2002	3.482387116297811
2003	3.503973186921836
2004	3.0654128564056964
2005	2.8273991080520697
2006	3.191559182126131
2007	2.8433972756377814
2008	2.833167198479236
2009	2.8730689596266354
2010	2.359814766469988
2011	2.6118652061103513
2012	2.4545200699292127
2013	2.5774265749325025
2014	2.332379378284337
2015	0.8670399035185652