When I export my artboards (with 'Export as'), AI sometimes won't show whole range numbers, but stick to previously entered numbers for this file. This is fine.

But my problem is I often need to export all artboards, but not first. And I don't remember exactly how much of them I do actually have — this differs from project to project.
So I have to exit 'Export as' dialogue, go to Artboards palette, see how much artboards are there and return to exporting.

Why not to show how much artboards I do have inside dialogue window?
Please see mockup attached.