This. It also showed that mortality rate has been roughly halved since the 90s, but I wonder if that halving has been evenly split around the world, or if it is disproportionate to certain localities. [I'd assume the latter]
https://ourworldindata.org/where-are-children-dying
In summary, it's highly disproportionate, with rapidly industrializing nations in Asia representing a huge portion of the decline in child mortality.