This web page had a reading level of Grade 12 and a reading ease score of 40. Americans average a reading level of Grade 8, so 12 is harder than the average American can read. For the reading ease score, higher is better. Comic books are at 90, and legal documents are often 10 and under.

https://www.blog.theteamw.com/2011/01/23/100-things-you-should-know-about-people-54-the-average-reading-level-in-the-usa-is-grade-8/