How to Add a Second Y-Axis on Excel & Make a Second Series at the End of the Chart. Microsoft Excel charts give you a large number of options for displaying the data in your spreadsheet.

To add more data to the Y axis in a line chart, add additional numbers in cells below your existing data. Right-click the chart, choose "Select Data" and highlight all entries in the single column.

In the Format Data Series pane, click Secondary Axis and change the Gap Width to 500%, as shown in Figure G. Doing so reduces the bar’s width so it looks less like a column and more like a line.