Year	% of total
1970	6.1335209131217745
1971	6.147347227244339
1972	6.114033598028344
1973	5.984463508848478
1974	5.825815341381238
1975	5.4383604302820725
1976	5.19165102637289
1977	5.979654481202925
1978	5.967485327830354
1979	5.900852090342419
1980	7.152506746796967
1981	9.276439928280988
1982	7.793626675083395
1983	7.777091337521915
1984	8.503656608974993
1985	7.722198950604541
1986	7.089614210646973
1987	6.520984961437222
1988	6.78648165458159
1989	6.726285191454322
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