> Tax receipts as percentage of GDP have been remarkably stable over time
That may be true, but since the sources you listed contradict each other, I'm left confused. I can find supporting evidence of the graph[1], but not of the wikipedia entry. The world bank apparently thinks they are all wrong[2]. Then there's a report that Norway is actually doing it with much less taxes than Denmark and Sweden[3], but that might be likely due to oil revenue. I'm left to conlcude that without a lot of research to look into the specifics, there's quite a few ways to measure this, and I'm not sure which are most relevant to the discussion at hand.