Amazon Prime, the company’s $99-per-year loyalty program, now has 54 million US members, according to a new analysis from Consumer Intelligence Research Partners (CIRP).
That’s up 35% from this time last year — again, based on CIRP estimates; Amazon itself doesn’t reveal anything but the hazy “tens of millions” when talking about Prime subscribers.
Of the 14 million members Amazon added in 2015, 7 million joined during the fourth quarter holiday-season.
Interestingly, CIRP points out that growth was spread more evenly this year in large part because of “Prime Day,” the holiday Amazon invented to celebrate its 20th birthday.
The loyalty service gives users free, two-day shipping on millions of items, as well as access to of thousands of free TV shows, movies, music, and books and unlimited cloud storage for photos.
Amazon can afford all those “free” perks and its occasional Prime price discounts because research from CIRP and others has long shown that Prime members spend much more on the site than non-members do.
This latest analystis shows that members spend ~$1,100 per year, compared to ~$600 per year for non-members.
That’s actually down from the beginning of 2015 though, when CIRP wrote that Prime members spent $1,500 per year, on average, compared to $625 per year, for non-members.
CIRP bases its insights on a survey of 500 US subjects who made a purchase on Amazon between October and December.
Disclosure: Jeff Bezos is an investor in Business Insider through hispersonal investment company Bezos Expeditions.