Conditional formatting based on a column total in WebI

I have a situation where I am calculating averages in a WebI report which is based on a BEx query.

Column C is my average and is equal to b/a.  The bottom line number in grey, 1.67 is a division of the totals for column A and B.

What I want to do is for values greater than the total value of 1.67, color them red.  Less than or equal to 1.67 will be colored green.

I have tried creating a variable as a calculation and dimension for sum(B)/Sum(A).  The variable I have created for C=B/A.  The totals, and hence the averages will change when looking at different time periods.

My final output would look like this:

Your assistance is appreciated.

Thank you in advance.

Lou