Year	% of total
1970	7.4936117326583815
1971	7.502457435644142
1972	7.902184398016085
1973	8.572367196432797
1974	8.028136431145697
1975	8.118582228890098
1976	7.377557334880463
1977	8.111906443245104
1978	7.084694791309114
1979	6.668769644600669
1980	6.775161321067685
1981	6.515644367274019
1982	6.943422626397829
1983	6.824161563197337
1984	6.403761539710455
1985	5.447908700534059
1986	5.063961402084416
1987	5.034776455909853
1988	5.08867548321259
1989	5.022047662314856
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