At the end of March, analyst firm Chitikia determined that iOS had been installed in over 80 percent of Apple’s supported iPhone, iPad, and AppleTV systems.

Today Apple has confirmed this rate, and released a graph showing the use of its iOS versions measured over a period of 7 days, ending yesterday.

This measure by Apple was done using data from its App Store, which shows an 87 percent adoption of iOS 7 since its release, with iOS 6 holding onto 11 percent, and the rest using about 2 percent collectively. This might be a more accurate approach than Chitikia’s use of Web traffic sampled from a number of different sources, since access to the App Store for updates is built into iOS devices.

This news comes only a few months before the expected announcement of iOS 8 at WWDC, which kicks off in the early part of June.

Apple’s upcoming iOS 8 is rumored to have a new Healthbook service for tracking personal health, an overhaul of Apple Maps, iTunes Radio as a standalone application, VoiceOver, and new features for Notification Center and Messages. In addition, iOS 8 is rumored to have mobile versions of Preview and TextEdit.