Interesting chart but is a nation's health directly correlated to infant mortality? Why not some other metric like median life-expectancy?

Median life expectancy is a weaker measure, because many people live in more than one country during their lives.

Infant mortality reflects a wide range of health issues: medical care, clean water, nutrition, access to medicines, etc.

Interesting to see the US, with its expensive (and much vaunted) medical care lagging behind other big countries with similar incomes, most of which have a more socialist structure...