Only 6% of iPhone 6 users have used Apple Pay

"Six months since the launch of Apple Pay, only 6 percent of iPhone 6 owners have used Apple Pay and 85 percent of people with access to Apple Pay have never used it, according to a report by InfoScout and PYMNTS.
The new stats were revealed at PYMNTS.com Innovation Project 2015 mobile payments conference. The survey drew on 1,188 participants over a three-day period last week.
Consumers who don’t use Apple Pay reported that they were happy with their current payment method and/or didn’t understand how Apple Pay worked. About 9 percent of iPhone 6 owners have played around with Apple Pay, but haven’t actually used it. They say they either forget to use it in stores or were unsure about where it was accepted."

Source:  Venture Beat, 18th March 2015

Note - I'm assuming this research is US only - as Apple Pay is only available in the US it would be a completely different story if only 6% of global users had ever used it