Why does Android 3.x have no market share?

According to the [Android Developer Dashboard](http://developer.android.com/about/dashboards/index.html) , the market share of Android 3.2 is only 0.1%, and no other 3.x version has even as much as that. Versions 2.x and 4.x have all the market share. Can someone please explain why there's a whole major version of Android that is apparently unused, while the previous and the next major versions are in wide use? Was 3.x quickly replaced by 4 and all devices forced to upgrade? What would have made 3.x so bad that no one uses it?