https://www.theverge.com/2018/4/18/17254388/jeff-bezos-amazon-prime-100-million-subscribers-announcement

Amazon CEO Jeff Bezos has revealed in his annual shareholders letter today that his company has over 100 million Prime members, marking the first time in the 13-year history of Amazon offering its Prime membership that the company has ever revealed its number of subscribers.

Analysts have speculated for years as the scope of Amazon’s premium service, which Amazon has kept secret for years. According to Bezos, Amazon Prime also saw its best year ever in 2017, with the company shipping over five billion products with Prime and signing up more new members than in any previous year.