Year	% of total
1970	0.29456761277530535
1971	0.5269129570498372
1972	0.5265424300047353
1973	0.5030742814561738
1974	0.5982008193502246
1975	0.5149048615393264
1976	0.603893663789118
1977	0.5600656006257517
1978	0.575454099218207
1979	0.43369492188599196
1980	0.5758764353482901
1981	0.7149290498180373
1982	0.629104989084999
1983	0.6624044159331643
1984	1.1007155029941407
1985	1.1373743764448228
1986	1.2193744043837356
1987	0.7445175723836529
1988	1.3361724461507174
1989	1.0926064500421713
1990	0.26246719160104987
1991	0.26195153896529144
1992	0.26109660574412535
1993	0.26195153896529144
1994	0.2628120893561104
1995	0.26298487836949375
1996	0.36549707602339176
1997	0.3720238095238095
1998	0.3364737550471063
1999	0.363901018922853
2000	0.3531073446327684
2001	0.41379310344827586
2002	0.3821656050955414
2003	0.3888888888888889
2004	0.3865267807840972
2005	0.44893378226711567
2006	0.5467800729040098
2007	0.5675368898978433
2008	0.6586826347305389