this.ultraChart1.DoughnutChart.BreakAllSlices = true;           

this.ultraChart1.DoughnutChart.Labels.Visible = false;

this.ultraChart1.DoughnutChart.Labels.LeaderLinesVisible = false;

ChartTextAppearance textApp = new ChartTextAppearance();

textApp.Row = -2;

textApp.Column = -2;

textApp.Visible = true;

textApp.ItemFormatString = "<PERCENT_VALUE:#>%";

this.ultraChart1.DoughnutChart.ChartText.Add(textApp);