I have a chart plotting unique website hits for our website. Number of hits is on the Y Axis and the Month/Year on the X Axis. I want to add a vertical reference line for November signifying the launch of the new website. How do I do this? I am comfortable with adding a Y Axis reference line but I don't know how to do it based on the X axis (Date). In chart properties > Presentation > Add reference lines the "Continuous X" option is greyed out.
