Year	% of total
1970	86.66890061788854
1971	86.87726297229666
1972	89.05165837077446
1973	87.35484034222274
1974	83.03496610977051
1975	79.51269839038449
1976	73.43014175592091
1977	74.27225928171957
1978	71.69753594291629
1979	70.43953613152726
1980	69.54985811186584
1981	69.48128024917938
1982	70.4040283229996
1983	68.8996728437376
1984	70.42241327813035
1985	69.99602696739828
1986	65.89648364168362
1987	68.37308800960454
1988	65.19546317717081
1989	68.36870171546293
1990	54.54545454545454
1991	52.17391304347826
1992	52.17391304347826
1993	47.82608695652174
1994	52
1995	52
1996	53.84615384615385
1997	50
1998	48.148148148148145
1999	50
2000	48.275862068965516
2001	50
2002	50
2003	44.44444444444444
2004	46.15384615384615
2005	46.15384615384615
2006	44
2007	46.15384615384615
2008	44