Counting consecutive underscores and reducing to 1 in VBS (in a file name)

In the code below, I have two underscores being replace by one underscore.  I would like to have any number of consecutive underscores replaced by one underscore.  So if there are 6 consecutive underscores in a file name, running the script will reduce that to one.

Set objFSO = CreateObject("Scripting.FileSystemObject")
nCount = 0
currentDirectory = left(WScript.ScriptFullName,(Len(WScript.ScriptFullName))-(len(WScript.ScriptName)))
set rootFolder = objFSO.GetFolder(currentDirectory)
renameFiles rootfolder
enumFolders rootFolder
wscript.echo nCount & " Files have been renamed."
function enumFolders(folder)
   for each sFolder in folder.subfolders
      renameFiles sFolder
      enumFolders sFolder
   next
end function
function renameFiles(nFolder)
   for each oFile in nFolder.files  
 if instr(oFile.name,"__") > 0 then
         newFileName = replace(oFile.name,"__","_")  
         newFilePath = left(oFile.path,len(oFile.path) - len(oFile.name)) & newFileName
         objFSO.MoveFile oFile.path, newFilePath
nCount = nCount+1    
end if
next
end function