Where do I look for cached data size on Statistics page

Thanks for the question. I guess I better update my documentation.

The bottom of the Statistics page shows a Cache Usage section. The right column of that section shows usage in megabytes.

The first two rows (Pages Used and Pages Free) show the overall use of the SQLite database. The rest of the rows show how that usage breaks out by the various kinds of data items in the cache.

I hope this helps.