Why are American households using less electricity lately? A blog post from a University of California-Berkeley business prof shines a light (sorry!) on a big reason why — efficient light bulbs have a bigger share of the market.

The big change: Per-capita power use plateaued around 2010 after decades of growth, and is now lower than it was five years ago, notes Lucas Davis of the Energy Institute at Haas.

Data: Energy Information Administration; Note: Percentages do not add up to 100% due to rounding; Chart: Andrew Witherspoon / Axios

One level deeper: Over 450 million LED's have been installed as costs have dropped 94% over a decade, compared to less than 500,000 in 2009. Use of compact fluorescent bulbs has also surged.

• While appliances like dishwashers and air conditioners have all gotten more efficient, that can't explain the decrease in household power use yet. "The turnover is too slow, and the gains in energy-efficiency for these other appliances have been too gradual for these changes to explain the aggregate pattern," Davis writes.

A helpful new Energy Information Administration snapshot provides details about the growing adoption of efficient lighting and what's driving the change including: federal lightbulb efficiency standards that took effect in 2012, state policies, utility programs and falling costs.

A survey conducted in 2015-2016 found that 86% of households used at least one CFL or LED bulb, and nearly a fifth of the all households reported using no traditional incandescent bulbs.