Well, I Googled it, before I asked, and at the very least it's a thing that people do track. The stats are available. The concept includes the very considerations that you mention: net assets minus debt. So, yeah, I'm sure there are periods where one can get underwater, and, like you say, where you can as an individual can rate at a low point, or underwater, but still be able to carry on. But I have to think that something like this, more than the Dow or whatever, is actually the stat that makes most households feel more or less secure, more or less prosperous. And therefore how we'll know when America has been made to be great again.