Many factors determine the overall elasticity of energy. Income levels are likely to play a part, together with the structure of the economy. Actual price levels vary widely between countries due to differences in existing taxes, which in the case of a carbon or energy tax implies that the percentage tax rate is higher in low-cost countries (USA, Canada) than those with high prices (Germany, Japan). The level of government intervention in such areas as efficiency regulation also varies widely. In a country where energy use is currently high and inefficient, there may be many low-cost opportunities for reductions, while countries that currently have lower energy intensity may find it harder to make further improvements.