Contactless payments continues to grow, especially in Europe.

Juniper Research forecasts that point of sale terminal payment transactions will jump to $500 billion next year from about $321 billion currently.

The bulk of the growth hinges on retailer adoption of contactless terminals, which has mostly occurred in Europe — led by the U.K. In the U.S., adoption rates are slower, and while consumers install contactless payment apps like Apple Pay and use it once, repeat usage lags.

The POS transactions, which are conducted in stores, include contactless cards as well as wearables and mobile devices with payment apps. And while $500 billion sounds like a hefty sum, it still represents only 5 percent of all of the global POS transactions expected to be occurring in stores in 2017, according to the Hampshire, U.K.-based Jupiter.

The research firm said the surge in contactless-enabled POS terminals began in 2015 and was driven by “retailer obligations to card companies in many markets to ensure that all terminals will be contactless ready by 2020.” It noted that this commitment is “likely to prompt an upsurge in migration to contactless payment.”

By way of example Juniper cited Visa, which said this past April that there were 3.2 million contactless terminals in Europe, which compares to 2.6 million in the same period last year.

“Contactless terminals now account for a significant minority of terminals in many regions (and in a majority in several national markets) and, as of the end of 2015, numbered 15.3 million, or nearly 20 percent of all POS terminals worldwide,” the researchers said. “These numbers will increase sharply over the next five years, with contactless accounting for more than two in three POS terminals by 2021.”

Research author Nitin Bhas said the study “pointed out that the frequency of contactless payments may indeed be limited in some markets.”

“This is mainly due to the lack of widespread availability of supporting POS contactless reader terminals and also that some potential users are likely to remain cash-centric,” Bhas said. “For example, Germany remains a highly cash-centric economy, with cash still accounting for around 57 percent of in-store retail transactions by value.”