What is the meaning of "relative importance" in the sentence below?
Overseas connections were almost restricted to the western maritime powers, in particular to Great Britain, France, Spain, Portugal and the Netherlands; and the relative importance of powers within this group had recently been greatly changed.
I know the meaning of "relative" and "importance" respectively, but somehow I can't understand the meaning of the collocation "relative importance" in the context above. Could you explain it in detail please?