Find individual users' backup size in Time Capsule
You'll want to get a tool like BackupLoupe to introspect each backup event to locate the largest files stored on each interval (or search across all backups to find large folders and files).

You could also use a command line tool like tmutil compare or du -sm /whatever/* to calculate sizes and changes - but a graphical tool with searching ability even when the volume is not mounted is far superior for the task of finding large users of space on a Time Machine volume.