Well, the black squiggly line in the opposite direction shows an increasing relative gap between races, which you don't care about.

It shows that while infant mortality has gone down for all, and even though it's significant, that black children are dying at an increasing proportion to their white peers. But you don't care that it fundamentally shows that they're not getting the same access to the same improvements (either medical care, education of the mother on prenatal care, etc).