Krugman on Education

A recent Paul Krugman column made a puzzling assertion about education:

The rise of American education was, overwhelmingly, the rise of public education — and for the past 30 years our political scene has been dominated by the view that any and all government spending is a waste of taxpayer dollars. Education, as one of the largest components of public spending, has inevitably suffered.

It's hard to know what precisely he's saying here, but he seems to be trying to imply that education has "inevitably suffered" because of a lack of government spending.

Any such implication would be difficult to defend. As you can see in the above graph (from an Education Next article by Arthur Peng and James Guthrie), education spending has skyrocketed in real terms precisely during the period during which, according to Krugman, our politics were "dominated" by an anti-government-spending view. So what's the counterfactual here -- how much more does Krugman think we should have been spending?