I am trying to create a chart that has the primary axis as a stacked chart that shows 2 figures (numbers of sales & number of referrals). I am then adding a line that shows percentage across the chart in a secondary axis. The issue is that I need this line to show the percentage of sales that were referrals. I have the chart created, however due to the referrals changing each month the line is not accurately showing the percentage. The percentage number is correct; it is the spot where the line intersects that is not calculating properly on the stacked bars. Any thoughts?