Year	% of total
1970	4.464668243297106
1971	4.440175792853706
1972	4.511771270445709
1973	4.257280401471938
1974	4.000413847457653
1975	3.7392383098622783
1976	3.7066522874176515
1977	3.2627814577884218
1978	3.654793732562113
1979	3.5840855405386978
1980	3.5485393641285765
1981	3.903429962816108
1982	3.805880929244629
1983	3.7691674019694523
1984	3.846511801186562
1985	3.4366404446078387
1986	3.5197205697590164
1987	3.4995160177105347
1988	3.152947354649798
1989	4.613257473797341
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