The cool way
There’s a font for this called FF Chartwell (no affiliation), which I have personally used for different annual reports and white papers. All the data is editable as numbers via the Story editor in InDesign, as the presentation video shows.
Each of the styles below sells as a separate font for about 20$. What you probably need is the ‘FF Chartwell Bars Vertical’ seen in the first graph below.
If you must construct this chart inside the table
I would use the black square character found in Arial. Any other font would work if it includes a square-looking glyph. I would insert this in each cell and construct the bars by scaling and positioning this inside the cell. With the proper settings it could be perfectly aligned inside each cell, then size it by doing some simple math.
You could extend the 100% value to 1000% horizontal scaling, then multiply with 0.94 for the 94% value and so on. This way you are not linking external files, not using anchored objects or overlays, and the bars will stay in place whatever other edits you do to the table.