Year	% of total
1971	0.6004632860245896
1972	0.5314249127516929
1973	1.0614885369121985
1974	0.9861227162787441
1975	1.0767746744158513
1976	1.171121748771318
1977	0.769952267319835
1978	0.7865533668571887
1979	0.7272470661392482
1980	0.689631078501975
1981	0.6669320754123477
1982	0.42956142064403463
1983	0.6809064361551823
1984	0.7214169605512485
1985	0.8068050791004182
1986	0.7591391029869065
1987	0.7038989962295623
1988	0.7096691430959016
1989	0.5003026207833109
1990	8.258073843804647
1991	7.916275777568653
1992	7.850396932583083
1993	7.72138477000095
1994	6.939031728888823
1995	6.972381322705903
1996	7.590497894723367
1997	7.314894941489106
1998	6.843931695909673
1999	6.321707998288175
2000	6.780808219056874
2001	6.604705564149796
2002	6.37754556912657
2003	6.1213572377263565
2004	6.126226446922125
2005	5.921434424499608
2006	5.711876884640801
2007	5.50619704930623
2008	5.063109018013612
2009	4.762139171983602
2010	5.045824802740473
2011	5.074438518159888
2012	4.872511133622323
2013	4.5609924976730385
2014	4.543310308051622