A more visual description might be that 16 pounds of the material would replace 100 pounds of steel - for the truly impaired a graph might be necessary.
Yup, this is the sort of thing to make space colonization more viable. The one hitch is that a lot of the mass of the ship going into space is the fuel needed to lift the weight of the fuel. It makes for a bit of an exponential cost. Lighter, more weight-efficient fuels will make a greater impact, I think.
But, well, you DO gain a lot by shaving off fractions of 1%, in this sort of thing.