you have to edit the CvMainInterface.py, a file often used by other mods too
Now you're tempting me to look at that file and get a little familiar with this.
I think the user interface really is missing another button in the lower left (where the other UI display change buttons are), and that missing button would add these bars/icons, preferable below the upper right buttons which lead to the advisor menus, so you can quickly clutter the screen with percentage icons, all near their associated buttons which currently give the details.
Anyways - there are always obstacles. All of them can find a way to be overcome if enough people want it to happen.