You're misinterpreting the data and over-extending the definition of " scoring below proficient on national literacy tests".

The data from here: https://www.aecf.org/resources/2022-kids-count-data-book/aux...

Table 1.6. Confidence Intervals for States and Nation, 2009 and 2019 New Jersey 2019:

58.1% Percent of fourth graders not proficient in reading