Year	% of total
1970	5.772218560303697
1971	5.481096670630471
1972	5.376104986746433
1973	5.428854945476173
1974	5.14330615392448
1975	5.063539826143123
1976	4.70606719824346
1977	4.800306626510011
1978	4.447724708985565
1979	4.50422808967862
1980	4.31363014261859
1981	4.413582313900585
1982	4.334649863641578
1983	4.26365977748851
1984	3.9391917451357257
1985	3.303312081557023
1986	3.027539670922603
1987	2.676103399021146
1988	2.5449804405109333
1989	2.436529146702389
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