Year	% of total
1970	6.896916055452286
1971	6.806840606915538
1972	6.704992478188827
1973	6.660303099756279
1974	6.561036201766661
1975	6.572926770688915
1976	6.338442120547461
1977	6.150542244942843
1978	5.979075292793336
1979	5.861069866652162
1980	5.6456699008848314
1981	5.586881472464884
1982	5.448465427079325
1983	5.389334257394105
1984	5.392492655131945
1985	5.744399910756327
1986	5.692098344117439
1987	5.604387642478033
1988	5.665850853511921
1989	5.54164577177009
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