If you have a chart in which you want to display two column values that differ significantly, i.e. the scale of the value axis must not display the column values together, you must add a secondary value axis.
This is what you do:
1. Click the chart.
2. Click the Layout tab.
3. Click the list arrow to the right of the top pane in the Current Selection sub-tab.
4. Click the series for which you want to add a secondary axis.
5. Click Format Selection in the Current Selection sub-tab.
6. Select Secondary Axis.
7. Click Close.
8. Right-click the secondary bar series.
9. Click Change Series Chart Type in the shortcut menu.
10. Double click a line chart type.