Hi Astrid,

To align the zeros on both the primary and secondary axis, you can follow these steps:

1. Select the chart and click on the secondary axis to select it.
2. Right-click on the secondary axis and select "Format Axis" from the drop-down menu.
3. In the Format Axis pane, under "Axis Options", change the "Minimum" value to -50% (or the minimum value of your data, whichever is lower).
4. Under "Axis Position", select "On Tick Marks".
5. Close the Format Axis pane.
6. Right-click on the secondary axis again and select "Format Axis" from the drop-down menu.
7. In the Format Axis pane, under "Axis Options", change the "Maximum" value to 50% (or the maximum value of your data, whichever is higher).
8. Close the Format Axis pane.

Now, the zeros on both the primary and secondary axis should be aligned. If you need to adjust the position of the secondary axis, you can click and drag it to the desired location.