Google has released some statistics that show the breakdown of how many people are using the different variants of Android. The fact that 37.2% are still on 1.5 should be a great source of concern for the company.

Android 1.6 users take up 29.6% of the Android population, with 32.4% running the latest version 2.1 of the software. The rest, about 1%, are using a mix of Android 1.1, Android 2.0 and Android 2.0.1. That breakdown also offers some insight into how many people are using different Android devices.

The vast majority of users running 1.5 will be HTC Hero owners, who have still not been offered an upgrade to 1.6, more than 6 months after it was made available to other device owners, let alone 2.0 or 2.1. People running 1.6 will be mostly HTC Magic owners, and those on 2.1 will mostly be people who've shelled out for an HTC Desire, HTC Legend or a Nexus One.

The fragmentation of the Android market continues to be a problem for Google, as the company has so far failed to force handset manufacturers to issue device updates. With more and more apps unavailable to the largest segment of Android's user-base, how loyal will those users stay?