TIL! Looks like that flipped around 2000: https://pubmed.ncbi.nlm.nih.gov/18924533/

This goes into some more detail: https://en.wikipedia.org/wiki/Okinawa_diet#Longevity

That's because lots of US troops are stationed in Okinawa and with them came lots of fast food chains. Young(er) people in Okinawa eat lots of junk food, and they have shorter life expenctancy than their parents.