Apple Pay saw one million credit card activations within its first 72 hours of availability, Apple CEO Tim Cook said on stage at the WSJD Live Global Technology conference Monday night.

This makes it the largest mobile payment system yet, Cook claims.

The mobile payments space is still fairly new, so it's hard to tell exactly what those numbers mean.

Although Google hasn't spoken on numbers regarding its own mobile payment service, the Google Play Store says Google Wallet has been downloaded anywhere between 10 million and 50 million times.

That's a wide margin, but download milestones The Guardian obtained from the Internet Archive show that the mobile payment app passed the one million install mark in August 2012. That's a little more than a year after the service launched in May 2011.

The number of installs doesn't provide a completely accurate comparison, since it's unclear whether or not those people actually ended up using the service. But, it does provide some perspective as to how many consumers were interested in Google Wallet.

Although Apple seems to have convinced a decent number of users to sign up for Apple Pay relatively quickly, some retailers are refusing to adopt the system. Rite Aid and CVS are among these merchants, and it's unclear exactly why they're blocking customers from using Apple's new payment service. Some have speculated it's because of the Merchant Customer Exchange, a consortium of the largest retailers in the US, which happens to be testing its own mobile payments service.

This, however, doesn't worry Cook, as he said on stage that "over the long arc of time," retailers will have to do what consumers want. Basically, it sounds like he's saying that if Apple Pay becomes massively popular, retailers will adopt it in due time.