Showing Data Point Symbols in Area Charts
In area charts, you can use symbols (circles, triangle, squares, and diamonds) to
represent data points.
To show data point symbols:
Select a data series (area shape), click Inspector in the toolbar, click the Chart inspector
button, and then click Series.
Choose a symbol from the Data Symbol pop-up menu.
Adjust the size of the data point symbols by entering a value or using the stepper in
the adjacent field.