Year	% of total
1971	0.1402175182772193
1972	0.12266795295745206
1973	0.24478397422391332
1974	0.39649788291596255
1975	0.6394272952708325
1976	0.813632081875534
1977	0.671680175296769
1978	0.7061685902335105
1979	0.650131541421647
1980	0.5873772276004576
1981	0.7281715462903049
1982	0.6680603647989104
1983	0.8262105943438729
1984	1.0635182582594198
1985	1.1941591696928981
1986	1.0807667794545703
1987	0.9827464456335906
1988	1.1311983934618077
1989	1.0232181324390432
1990	6.133297507403433
1991	5.987304712833735
1992	5.881863212485408
1993	5.807586232575931
1994	5.4235560629871165
1995	5.508460074173655
1996	5.838591946786015
1997	5.72120663836729
1998	5.4313959461706345
1999	5.5184392135277
2000	5.651826801983998
2001	5.762136948269449
2002	5.722121801030941
2003	5.741622062929242
2004	5.395590394956088
2005	5.1564686553018015
2006	4.95264099907306
2007	4.667210825568507
2008	4.566965247533282
2009	4.418851363335503
2010	4.2486481176228885
2011	4.232937639962036
2012	4.168261310490343
2013	4.024982526203457
2014	4.16184730367687
2015	0.09176541108159356