How can I ignore properties according to their value with XmlSerializer

I'd like the XML created by XmlSerializer to exclude properties if they have a default value. Is this possible with XmlSerializer or am I going to have to look into IXmlSerializable?

For example, I may have the following class:

public class PositionedObject
{
   public float X
   { get; set; }

   public float Y
   { get; set;}
}

I'd like to tell the XmlSerializer that when it serializes an instance of PositionedObject, to not include X if the value is 0 (and same with Y if it is 0).