I don't know many people, but I do know (not personally, he's in my school) who can't read. When we are reading out loud it takes him somewhere around a second

I don't know many people, but I do know (not personally, he's in my school) who can't read. When we are reading out loud it takes him somewhere around a second per word. 20% seems really high to me, but I'm also in school and don't really know anyone else, so if someone can't read in school there must be more somewhere outside of school. But I would like to see that study.