How to get usages for all users

I'm wondering is there any way to get bandwidth and disk usages for all users through command line or API at once,
I want to store these data in my own database, And I don't want to request it for each user separately.

Any help would be much appreciated.

http://directadmin.com/search_versions.php?query=api

http://directadmin.com/features.php?id=495