SOURCE: U.S. Department of Education, Institute of Education Sciences, National Center for Education Statistics, National Assessment of Educational Progress (NAEP), 2003, 2005, and 2007 Reading Assessments.
NAEP started collecting data by U.S. census regions in 2003. To see more information about the states contained in each region, see NAEP reporting groups
To read more about achievement levels and how they are set, see Reporting the Assessment—Scale Scores and Achievement Levels.