Amazon PrimeBloomberg reported.

has reached a milestone number of subscribers: CEO Jeff Bezos says the service now has more than 100 million members. The announcement came in Amazon’s annual shareholder letter, which was published on Wednesday (April 18),

Traditionally, Amazon does not release its Prime subscriber count. As a result, analysts have had to estimate its subscriber base through shopper surveys.

Beyond the subscriber count, Bezos said in the letter that Amazon has shipped more than five billion items to Prime customers, and also stated that 2017 saw the highest number of new Prime sign-ups. In addition, Amazon had its best year for hardware sales in 2017. Even so, Bezos said that the eCommerce giant will continue to invest in growing its customer base, along with Amazon’s infrastructure and brand.

The news comes a few months after a study found that Amazon Prime subscribers spend an average of $1,300 per year, and that its subscriber base continues to grow their spending. According to Fortune, the Consumer Intelligence Research Partners (CIRP) estimates that Amazon currently has 90 million U.S.-based Prime subscribers. In fact, 63 percent of the eCommerce retail giant’s customers are Prime members, and in the 12 months leading up to last October, the total subscriber base has grown by 38 percent.

The study, which includes data from 500 Amazon customers, estimates that Prime subscribers spend almost double the $700 per year that the average non-member spends on the site.

In addition, those with an Amazon Prime membership are happy with the perks they’re getting as subscribers, which include free two-day shipping, discounts on overnight delivery, access to Amazon’s streaming video library, free eBooks and more. The study found that 95 percent of Prime subscribers say they’ll either “definitely” or “probably” renew, up from 94 percent during the same period last year