The numbers are far worse than that. 30% of americans hit the healthy BMI range. But it's very easy for skinnyfats to slip into there. Overfat percentages give a better impression because it actually looks directly at the amount of fat on someone.  And by those numbers, as of 2017 only 9% of adults in the US aren't fat. While a lot more rough, I've seen estimates that place the amount of actually fit people even lower - at around 5%.