How about data from the OCED?

https://infographics.economist.com/2026/20260627_IRC330/2026...

>Many of [students] do very well—but a striking share perform abysmally (see chart 1). Across rich countries some 8% of students in tertiary education notch up a score in literacy no better than one might expect from a ten-year-old child. The share is about the same for numeracy. Worse, the share at or below this bar has risen since the tests were last run, a little over a decade ago. The share of very poor performers in literacy has more than doubled.

https://www.economist.com/international/2026/06/25/students-...