You can split the Y axis using bi-polar or dual axis chart types. when the Measures dimension (if available in the application) is placed on the Row or Column axis, you can also specify which members in the Measures dimension should be on the y1 axis and which should be on the y2 axis. The y-axis split enables the chart to display two Y axes.
Dual axis and bipolar charts have two Y axes when the Y axis split is used. The Y1 axis is on the bottom part of the chart and the Y2 axis is on the upper part, as shown in the following dual-axis chart:
The Measures dimension can appear on the X axis, filter, or legend. However, the Measures dimension usually appears as the legend. This makes it easier to distinguish which 1st and 2nd Y Axis items belong to each Measures dimension.
To split the Y axis when the Measures dimension is on the Row or Column axis:
When you click the Apply button the changes are implemented but the dialog box remains open.