Generally speaking, you'd have two dimensions, bar chart, stacked. I tried checkmarking "relative", but it looks like it's relative to the total, so you need to handle that part yourself. Something like this in your expression:
sum(whatever)/sum(total <SomeDimension> whatever)
Display as a percentage on the number tab. Probably go to the Axes tab and set a static max of 1, or it'll tend to go a bit above the 100% mark, not realizing that nothing will be above that.