How to: Show ToolTips on a Series
You can add a ToolTip to each data point on the series of a chart to display information related to the data point, such as the group name, the value of the data point, or the percentage of the data point relative to the series total when users hover over the data point in a rendered report.
You cannot add a ToolTip to a calculated series.
To specify a ToolTip on each data point
Right-click on the series or right-click on the field in the data field drop-zone, and click Series Properties.
Click Series Data and, for the ToolTip property, type in a string or expression. You can use any chart-specific keyword to represent another element on the chart. For more information, see Formatting Data Points on a Chart.