The table size for Maria and Aria storage engine types are printed as 'unknown'
This happens on the current version 3.3.8.1 as well as all versions below it
Only a simple code change is required.
Edit db_structure.php
Search for 'MyISAM' and add a case for 'Aria' and 'Maria'
Moved to Patches
Your patch was merged in the repository, thanks.