Since 2008, the cost of light emitting diodes (LEDs) has dropped by more than 85%. With this drop, the United States saw total installations of LEDs increase dramatically. In total, by 2012, more than 49 million energy-efficient LEDs were installed across the United States, representing an estimated $675 million in annual energy cost savings compared to traditional lightbulbs.
More facts on the evolution of lightbulbs, from the first "arc lamp" in the early 1800s in Great Britain through today's advanced LED designs, one can explore the U.S. Department of Energy's interactive online "History of the Lightbulb" website.
Photo and Graphic Credit:
 Photo of LED lightbulbs courtest of the U.S. Department of Energy
 Graph of LED cost versus total sales by Sarah Gerrity, U.S. Department of Energy