You can plot any number of reference lines required on the graph. Its very simple, follow below steps.
1. Plot the graph for required fields.
2. Then click on analysis pane on the left side of the screen.
3. Create a constant line with average for complete data.
4. Add the filter and now click on Reference line and drag and drop on the table.
You can observe the changes with 2 lines showing the difference. ( when the filter is removed both lie on the same line )
Hope this helps you.