Year	% of total
1971	0.13497976815615187
1972	0.11785381128575942
1973	0.23572670171386287
1974	0.3806071435410762
1975	0.615347278008534
1976	0.7836428065474667
1977	0.6471601998219806
1978	0.6825570539778985
1979	0.6293878762408917
1980	0.5693242660660225
1981	0.7061173129749584
1982	0.6479766924725178
1983	0.802119010314926
1984	1.0348616514983378
1985	1.1622274453808574
1986	1.0542855749200049
1987	0.9612708880418516
1988	1.1064526530507495
1989	1.0015853685974443
1990	6.0098534016003
1991	5.868350286378889
1992	5.7697273704720775
1993	5.699828296417223
1994	5.32017709915949
1995	5.40347853745248
1996	5.730881825134081
1997	5.61847971488207
1998	5.330345062322854
1999	5.41286103107449
2000	5.54133548513078
2001	5.646933836698241
2002	5.609640762549546
2003	5.633122179598045
2004	5.294226803080055
2005	5.059090049856631
2006	4.860666700434134
2007	4.583092048133628
2008	4.484921392759868
2009	4.339302557661226
2010	4.1737527486923796
2011	4.164023138711085
2012	4.104119812784058
2013	3.9673398284020314
2014	4.103154369878987
2015	0.09053645928640927