If you are looking to track this over time, you'll need to use a tool that is capturing this in snapshots and do some reporting over it.
Select snapshots.save_snap();
To see a size report between snapshots, list the available snapshots:
select * from list_snaps();
To get the size report, get the snap_id numbers you want to report between and run:
select * from snapshots.report_tables(<startsnapid>, <endsnapid>)