"N/A" rating is typically indicative of data inconsistency. Any known issues will be posted in this space.
A few states have reduced the frequency with which they report testing data to once per week (sometimes less than that). If a state's positive test average is 100%, this is probably the reason.
Risk levels as defined in the report published August 10, 2020 by the Pac-12 Conference Student-Athlete Health and Well-being Initiative (SAHWBI). See charts below: