DOE, Office of Energy Efficiency & Renewable Energy, Jan. 12, 2017, by Sarah Olexsak.
https://energy.gov/eere/articles/creating-sustainable-commute-electric-vehicles-and-workplace-charging

"In 2016, the plug-in electric vehicle (PEV) market exceeded expectations. Despite another year of unusually low gasoline prices averaging $2.24 per gallon, there are now more than half a million PEVs quietly zipping around U.S. streets. While PEVs are on the rise nationally, the Energy Department’s (DOE’s) Workplace Charging Challenge made big strides in 2016 as well."