The data are from the Energy Information Administration of the U.S. Department of Energy (DOE/EIA-0384(2008), June 2009). Hydro, wind, and solar electricity inputs are expressed using fossil-fuel plants’ heat rate to more easily account for differences between the conversion efficiency of renewables and the fuel utilization for combustion- and nuclear-driven systems. This enables hydro, wind, and solar to be counted on a similar basis as coal, natural gas, and oil. For this reason, the sum of the inputs for electricity differs slightly from the displayed total electricity output. Distributed electricity represents only retail electricity sales and does not include self-generation. The efficiency of electricity production is calculated as the total retail electricity delivered divided by the primary energy input into electricity generation. End use efficiency is estimated as 80% for residential, commercial, and industrial sectors, and as 25% for the transportation sector. Totals may not equal the sum of components due to independent rounding.