This is something liberals don't want you to know.
If they wanted you to know it, the liberal media would mention it when they write the sob stories about the suffering public schools, or the thundering editorials demanding more "investment" in education.
I don't read the local papers, but I'm pretty sure that in hundreds of stories along those lines they never once have told you the fiscal reality.
Facts are to liberals as a cross is to a vampire.
They prefer to play on your emotions, and hope you don't find any facts on your own.
They could, of course, claim that the increased spending is the reason for improved education.
That would leave them in the position of having to explain why they have been decrying "cuts," but they are a nimble bunch.
More awkward would be explaining why 30 years of increased spending produced no improvement until true education reforms were put into place.