Year	% of total
1970	0.7945991426930045
1971	0.8062442118749695
1972	0.8085043877696556
1973	0.8310469909044015
1974	0.8497928632830113
1975	0.8888394099638186
1976	0.8980430905054602
1977	0.9650655309155601
1978	1.0299363666671497
1979	1.1640442638540673
1980	1.3180566282681216
1981	1.3850963569056474
1982	1.357669240020173
1983	1.3791673158101683
1984	1.4474877833040904
1985	1.3853321430664078
1986	1.2969359350093401
1987	1.3001111208871423
1988	1.2394739078423553
1989	1.1455160423206328
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0
1996	0
1997	0
1998	0
1999	0
2000	0
2001	0
2002	0
2003	0
2004	0
2005	0
2006	0
2007	0
2008	0