DefaultLabelValue

DefaultLabelValue specifies a format for label values that will be displayed automatically if you do not specifically assign text to a chart series item.

• Use "#Y" or "#X" to display numbers from the X or Y axis respectively

• Use "#%" for a percentage of the total sum (of all items).

• Use "#SUM" to display the total of all items. 

• "#STSUM" displays the sum of a stacked series.

• "#SERIES" displays the series name.

• "#ITEM" displays the item name.

• You can also use the formatting described in this MSDN article Standard Numeric Format Strings. Use curly brackets to contain the standard numeric formats.  For example, you can display Y values as currency by setting DefaultLabelValue to "#Y{C}". See examples in the figure below.