Gross domestic product per barrel

Energy efficiency as it relates to oil usage can be described by the gross domestic product per barrel (GDP per barrel) (GDP/barrel) of oil used. The original data for this is taken from two sources, the CIA World Fact Book and the List of countries by GDP (nominal) article from wikipedia. It should be noted that many of the numbers from the CIA are mere guesses (see notes) and that many do not reflect the use of oil consumed in the process of making refined products.

Calculations
GDP/bbl is calculated by taking the GDP * 1,000,000 and dividing by the bbl/day * 365 to give dollars (USD) of GDP per barrel of oil.