This is a percentage value that must be between 0 and 100. The developer is responsible for setting a value appropriate to display a presentable chart. Large values for SpanPercentage tend to make the Legend box appear larger than the chart, and can make the chart unreadable. Very small values for SpanPercentage may make the Legend box unreadable.
The dimension spanned by the Legend box is the width of the chart control area (when Location is set to Left or Right) or its height (when Location is set to either Top or Bottom). This area can be shortened by setting the Margins property.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2