[rahmeero]

This data is from the California Dept of Education. I wonder if other states track this also.

My guess is that some states don't even bother, and their students likely don't perform as well. Then there are other states, small ones like Connecticut, Rhode Island and Vermont, whose students might fall on the high side of the curve.

Just a guess. Anyone know?

[snowwrestler]

States have to track these sorts of metrics to qualify for federal education funding. This is an enduring result of the “No Child Left Behind” act. Before that, you were correct, many states did not track educational stats in any consistent or reliable way.