The efficiency of energy use in growing the U.S. economy has made dramatic improvements over the past 60 years.  Before the mid-1980s electrical energy usage grew faster than GDP growth but since then the relationship has reversed.  Projections by the U.S. EIA (U.S. Energy Information Agency) indicate that GDP growth should be 2-3 times greater than electricity usage growth over the next 25 years.  In the 1950s electricity use grew about twice as fast as did GDP.  The ratio today has reveresed with GDP growing about 2.5 times faster than electricity usage.  That change corresponds to a 5-fold improvement in the efficiency of electricity usage as measured by GDP growth.