That seems high, because I think the literacy rate today is lower. I guess it depends on how you define literacy, though.
Four in five U.S. adults (79 percent) have English literacy skills sufficient to complete tasks that require comparing and contrasting information, paraphrasing, or making low-level inferences—literacy skills at level 2 or above in PIAAC (OECD 2013). In contrast, one in five U.S. adults (21 percent) has difficulty completing these tasks (figure 1)
That seems high, because I think the literacy rate today is lower. I guess it depends on how you define literacy, though.
https://nces.ed.gov/pubs2019/2019179/index.asp
Yes the literacy rate has actually been dropping IIRC.