///<summary>
 /// Writes this ExternalCountry.Population to the specified stream.
 ///</summary>
 ///<param name="writer"> the output stream to write to</param>
 ///<param name="obj"> the object to serialize</param>
 ///<exception cref="IOException"> if an error occurs</exception>
 public override void Serialize(HlaEncodingWriter writer, object population)
 {
     try
     {
         writer.WriteHLAfloat64BE((double)population);
     }
     catch (IOException ioe)
     {
         throw new RTIinternalError(ioe.ToString());
     }
 }