Microsoft today announced the latest Windows 10 Fall Creators Update (version 1709) was the fastest Windows 10 release to reach 100 million devices, “all while achieving higher customer satisfaction ratings compared to prior updates.” We don’t know exactly how many out of Windows 10’s 600 million users (as of November 2017) are running the latest version, but it’s safe to say the figure is probably over 20 percent.

Windows 10 is a service, meaning it was built in a very different way from its predecessors so it can be regularly updated with not just fixes, but new features, too. Microsoft has released four major updates so far: November Update, Anniversary Update, Creators Update, and Fall Creators Update.

Microsoft today also shared that the Fall Creators Update is now fully available for all compatible devices running Windows 10 worldwide. The company started pushing out the Fall Creators Update on October 17, meaning it took nearly three months for the team to be confident it is ready for everyone to download and install.

Here is why the process takes so long:

Full availability is the final phase of our rollout process. When a new feature update is released, we begin by targeting a select set of devices that we believe will have the best update experience based on device characteristics and testing done by us and our device partners. We then monitor feedback for issues around application and device compatibility and make adjustments along the way, if necessary. Actively listening for and responding to issues as they emerge helps us confidently expand the release to additional devices while maintaining a quality experience.

The percentage should get another boost next week: Devices with Windows 10 Pro and Windows 10 Enterprise editions configured to receive updates automatically from Windows Update will be offered version 1709 “after January 18, 2018.”

If you still don’t have the latest version of Windows 10 and don’t want to wait, follow this guide.