More (not so) fun facts:
54% of American adults read below a 6th grade level.
21% read below a 5th grade level, which is considered functionally illiterate.
High immigration numbers don't fully explain it either, as first gen immigrants only make up about 1/3 of those with low literacy.
Something that I did find is this. Its US-only and doesn't actually provide the numbers, but it tells you the general trend.
Ah, found one that does. 2022's decline seems pretty significant, in both mentioned subjects.
But so can bad health outcomes, learning environments, etc?
Yeah that's possible. Maybe in a few years, if the statistics stay the same, it's a teaching failure.