I wonder where TFS would be on this graph. Not that I think it competes well on merit with these others, but it still has some market forces pushing in its favor. It would be interesting to know how it compares.
Assuming tfs is not toyota financing services it appears tfs is microsoft's souce code management system and therefore is most likely not going to show up on debian's popcon.
My last employer was still on sourcesafe (shudder!) when I left last year, and I'd bet they'll eventually go with something from SourceGear or Seapine before heading down the TFS path.