Query about creating a % graph

Hi. I have a list of customer transactions in my DB. Now I have created a graph which tells me how many transactions happened per week. That is easy. This is series 1.
Second graph is list of transactions basis a particular filter lets say amount > 500. This is series 2.

Now i want to have a graph which plots % by week of series 2 over series 1. For e.g. if total transactions in week 3 were 30 and >500 were 20, then i want to plot 66.67% as a point on the graph. How can i do that?

That is not possible, you can open a feature request: