21% of adults in the US are illiterate in 2024.
54% of adults have a literacy below a 6th-grade level (20% are below 5th-grade level).
https://www.thenationalliteracyinstitute.com/2024-2025literacy-statistics
Specifically it is about 75% of the population being functionally or clinically illiterate as I said. This is more likely caused by the fact that American culture is anti intellectual, and not the lack of being taught etymology, as etymology has little to do with literacy.