note: this is a reformation of a previous question, see: How exactly does the Backup and Restore utility in Windows7 work?

I have per the task scheduler scheduled windows 7 backup and utility to run once a day. The amount of data I produce in a day is best measured in KiB yet, a few GiB of data is added to the backup destination set in the backup utility daily. Why is this? Is this due to this utility making what are called "normal" backups instead of "incremental" backups? If so, how can this setting be changed?