Developed Nations’ Tax Rate Comparison

Interesting data from the Organization for Economic Cooperation and Development as posted in the New York Times:

What’s even more interesting is the percentage-point change. Canadian, German, Dutch and British tax rates have basically remained the same since 1975. Seems to me there must be a relation to the stability of the economy somehow.

I’m not sure how “Tax revenue as a percentage of G.D.P.” translates into actual average tax rate, though. If Canada’s tax revenue is 33.4% of G.D.P. – is this percentage the average tax rate Canadian households pay?