I can find plenty of sources pointing to net education spend decline relative to inflation/gdp: https://www.macrotrends.net/countries/USA/united-states/educ... https://www.cbpp.org/research/state-budget-and-tax/a-punishi... https://edlawcenter.org/research/$600-billion-lost.html

https://www.cbpp.org/research/state-budget-and-tax/most-stat... The question is not really is it increasing — but how much it has increased and whether that actually affords a quality education. https://www.theguardian.com/us-news/2018/sep/07/us-education...

(Hint: it probably has to do with the fact teaching makes very little $ in most places and is not treated as a good career in the states)