Backups

I use Windows 2000 Server. I do a backup every night to a tape. the software I use is in Programs/Accessories/System Tools/Backup. My tape drive supports compression. Depending on the types of files I backup I obvisouly get a different compression ratio. What I would like to find out is; When the backup is complete, how musch of the tape was actually used? Does anyone know of somewhere I can go to see this information in Win2K Server?