Hey Jasmine,
I'm pretty sure that this System Smart List is universal for levels of Marketo.
If you don't have it, creating a smart list with the Unsubscribed filter being True should get you the data you are looking for.
When you say you emails missing from the report, how do you know that they are unsubscribed? Other reasons why folks are excldued from blasts are the have an Invalid email address, they have been suspended, or something as simple as they do not have an email address (I felt pretty silly when that realization popped in my head.)