I'm going to take a stab at this.
the sql table "restores" is probably for restartable restores. TSM server keeps restores sessions that were interrupted and that can be restarted by the client. See TSM client docs for restartable restores if you are interested.
Otherwise, I can think of two things
1) use TSM accounting file. I've written perl programs in the past that easily parse the information so that a manager can look and see how much data has been backed up by a client(s) or restored. I might want to say here that the numbers in the accounting file are a estimate of how much data is transferred since some of that data is also file metadata rather than actual file date.
2) set activity log to to 31 days and then use a perl activity log scanner that pulls out backup or restore data. Again, written stuff this tool before so I know it's very doable.
cheers
rick