The higher the average income of the people (as expressed through per capita GNP), the higher the tax rate.
As national income increases in a given country, the size of government as a portion of gross national product (GNP) rises and the range of services people expect the government to offer rises.
This is less than one-half of 1 percent of world GNP.
I suspect it is both; GNP rises, so we buy more energy, allowing GNP to rise so we can buy more energy.
An ongoing debate is whether a high amount of energy raises a nation or region's gross national product (GNP) or whether rising GNP increases the consumption of energy.
