While true in absolute dollars, it doesn't really seem to be true in inflation adjusted dollars.
https://drive.google.com/file/d/1ZbUD16t4aaM6rCOmFogjxkVhRpJ...
https://edsource.org/2015/states-in-motion-school-finance-na...
Even if it stayed constant per your graph, teachers are competing with growth in administrators for education dollars.
While true in absolute dollars, it doesn't really seem to be true in inflation adjusted dollars.
https://drive.google.com/file/d/1ZbUD16t4aaM6rCOmFogjxkVhRpJ...