Missing space in calculations of priv.stm/edb

Currently, my Priv.edb file = 9.3 GB and my Priv.stm file = 4.6 GB. But when I calculate the mailbox size on my mailbox store, it only comes to 2 GB.

What is taking up all the other 11 gig’s (13.9 – 2) of the databases?

I deleted unused mailboxes and ran an offline defrag this past weekend.

Thanks in advance !