Graphical Indicators

I use following indicators in progress reporting

Green Dot = planned progress-Actual progress is less than 10 %

Yellow Dot = if the value is 10 to 20 %
Red Dot = if the value is above 20 %

This is my problem

as per the above criteria , even if an activity’s finish is long overdue and is 90% completed , the indicator will be "Green"
i want to make it RED

ie : the indicator should be RED
if "Status Date" - "Finish" is more than 5 Days

how to do it in a simple way

thanks