Martin - I would be interested in the mechanics of how you put this together. I believe you are an AIQ user? Is this just a case of taking the numbers from reports and dropping it manually into Excel or do you do something within EDS?
If you subtract one set of data from the other you should be able to draw a single line chart in the form of a spread which you could then use within other screening routines.
I do it manually via AIQ EDS.... Basically I test for the numbers of stocks that have closed <&> 5% from open, and those that have closed within 1% of their high or low of the day.This is very much an experimental analysis of the general market breadth, analysing all 2,500 odd stocks on LSE... Then I drop the figures manually into excel which produces the 2 charts. An amazing feat for my computer application illiteracy
Makes a nice picture though
If you want to take the numbers and fiddle with them, be my guest!- It may produce a more interesting/informative chart.