How’s that possible? Federal spending (and in most states- spending in general) on public schools has gone up drastically in that time period...
You have the answer, spend more money on education and test scores will continue to go down.
We lived in Montgomery county in the late 90’s because of the “good education” system there. Our 1st grade daughter was having trouble reading(outcome based education was the flavor of the month), I asked her teacher about it, she said “don’t worry a lot of other kids are having the same problem” That was the day we became actively involved in our kids education. Needless to say, I consider Montgomery county schools singularly unimpressive.