I would like to add a secondary Y axis to a chart; I have followed instructions from other sites, which is:
r-click on chart
choose “Insert/Delete axes”
select “Secondary Y axis”
r-click on secondary axis, select “Format axis”, select “Positioning”, select “Category”, select desired position for vertical line
The problem is that the secondary axis will only appear on the left or the right of the graph - never in the middle.
The chart consists of three columns: dates (yyyy-mm-dd) and two columns of numbers
I need a vertical line to appear at a specific date to highlight a change in behaviour.
I would be most grateful for a solution!