The newcomers — Canada, Australia, Spain, Thailand and Hungary — join a cohort that also includes the U.S., China and most of Western Europe.

Why 5% is so important

Most successful new technologies — televisions, mobile phones, LED lightbulbs — follow an S-shaped adoption curve.

Sales move at a crawl in the early-adopter phase, then quickly once things go mainstream.

In the case of full-electric vehicles, 5 percent seems to be the inflection point. The time it takes to get to that level varies widely by country, but once the universal challenges of car costs, charger availability and driver skepticism are solved for the few, the masses soon follow.