Year	% of total
1970	2.2349902510456867
1971	2.3854501969491104
1972	2.3793516764320874
1973	1.8909200823004537
1974	1.9228473614935948
1975	1.5823730567736844
1976	1.3535009093741621
1977	1.2798383546877785
1978	1.0755294129232063
1979	1.1308753360820287
1980	1.6203887840809412
1981	2.1188163470047754
1982	2.3182170565946953
1983	2.4864627606534704
1984	2.5088971889286547
1985	1.339180949988633
1986	1.1529544789506494
1987	1.6060650337873368
1988	1.7752059865249927
1989	2.0171100565177813
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