In general, they list the CFM by the inches of static pressure there for you. If you want an "engineering estimate" for that curve at points not provided, take two of those points and solve for the equation H = H_0 - A*Q^2, where H is head, H_0 and A are constants, and Q is flow (just use the units given).
However, on a cursory glance, those CFM values seem astronomically high. I suspect that data is not valid. I would e-mail Grainger or the manufacturer to find a spec sheet.