Sets or returns whether the data label will contain the (y) value for the data point as a percentage. Only doughnut and pie charts can dispay values as percentages.

 public boolean ContainsValueAsPercentage{ get; set; }

Public Property ContainsValueAsPercentage() As Boolean

This defaults to false when creating a new Series.
The data label is considered disabled if this and ContainsBubbleSize, ContainsCategoryName, ContainsSeriesName, and ContainsValue are all false.
If the series category type is not a pie or doughnut chart, then this property has no effect.