Instagram announced at an in-office event today that it now has 1 billion users worldwide. It had 800 million users in September of last year, which was 200 million more than that same time the year before. The app just keeps steadily adding 200 million users a year, it seems.

“It’s incredible, and it’s something Mike and I never thought would happen,” co-founder Kevin Systrom said.

It’s unclear where most of these new users came from. Last year, most of the growth was attributed to the launch of Stories. Over the past year, the company’s expanded in-app creation tools by letting users add GIFs, emoji sliders, and polls to their stories. Meanwhile, Snapchat is still trying to grow its user base. It most recently averaged 191 million daily active users. Instagram also announced its new IGTV standalone app today that’ll feature long-form, vertical videos, in an attempt to compete against not only Snapchat Discover but also YouTube.