This example demonstrates how to use selection.each to create a context to access parent and child data simultaneously. The donut multiples are sized such that the area of each donut is proportionate to the total population, such that the area of the arcs is comparable across states.
This is a technical demonstration rather than a design recommendation; you probably don’t want to use this visual form. A normalized stacked bar chart is better at comparing the age distribution across states, and a stacked or grouped bar chart is better at comparing absolute values.