I was hoping for a breakdown by state within the US
My instant first thought, too!
They can apparently track "happiness" trends in postage stamp-sized countries in Central America, but don't bother to disaggregate the individual states of the U.S. Why?
Because happiness levels would correlate too closely with political affiliation, and it wouldn't be "politically correct" to point out that Dem-dominated states are generally miserable, pulling down the overall U.S. score.
Regards,