Energy intensity is defined as the ratio of energy used to some measure of demand for energy services. There is no one measure of energy intensity. The measure depends on the universe of interest being measured. If the universe of interest is an entire country, then the measure needs to reflect the energy used and the demand for energy services for that country. A country's demand for energy services is usually measured as the dollar value of all goods or services produced during a given time period, and is referred to as Gross Domestic Product (GDP). If the universe of interest is households, energy intensity might be measured as energy used per household or size of the housing unit. If the universe of interest is the iron and steel industry, the measure for energy intensity could be energy used per ton of raw iron...