As of release 3.5 Joomla is collecting stats data, thanks to the stats plugin (only works if it’s enabled), and it found too many websites are not using the currently supported release of 3.9.2. This data is based on the Joomla, PHP, and database version. These are some pretty alarming statistics, and should not be ignored! We have provided some links at the bottom of this article for your reference, review, and to even get the latest release of Joomla.
Keeping your Joomla website up-to-date
Source: Joomla Announcements