object[,] dataArray = { {1, GeoFieldType.geoFieldName}, {
                          2, GeoFieldType.geoFieldInformation}, {
                          3, GeoFieldType.geoFieldLatitude}, {
                          4, GeoFieldType.geoFieldLongitude}, {
                          5, GeoFieldType.geoFieldData}
                        };
MapPoint.DataSet dataSet = map.DataSets.ImportData(
  "C:\\temp\\Example.xls!Sheet1"
  , dataArray
  , MapPoint.GeoCountry.geoCountryMultiCountry
  , MapPoint.GeoDelimiter.geoDelimiterDefault
  , MapPoint.GeoImportFlags.geoImportExcelSheet
  );

object key = "inquiries";
Field field = dataSet.Fields.get_Item(ref key);
if(field != null) {
  object missing = System.Reflection.Missing.Value;
  DataMap dataMap = dataSet.DisplayDataMap(
    GeoDataMapType.geoDataMapTypeSizedCircle // DataMapType
    , field // DataField
    , GeoShowDataBy.geoShowByLatLong // ShowDataBy
    , GeoCombineDataBy.geoCombineByNone // CombineDataBy
    , GeoDataRangeType.geoRangeTypeDiscreteEqualRanges // DataRangeType
    , GeoDataRangeOrder.geoRangeOrderHighToLow // DataRangeOrder
    , 8 // ColorScheme
    , 6 // DataRangeCount
    , missing // ArrayOfCustomValues
    , missing // ArrayOfCustomNames
    , missing // DivideByField
    , missing // ArrayOfDataFieldLabels
    , missing // ArrayOfPushpinSymbols
    );

  if(dataMap != null) {
    dataMap.LegendTitle = "some title";
  }
}