It's driven principally by two things. One is certainly population growth and changing energy demand. For the other side of it, I'll go back to my earlier analogy of the roof. These assets do not last forever. It doesn't matter what kind of asset you're talking about. If it's a thermal asset, a nuclear asset, or even a hydraulic asset, a hydro plant, investment is required to bring it up to speed. So the largest portion of that investment, over $200 billion, is going to go into either upgrading existing generating facilities or building new generating facilities to meet the increasing demand.
In terms of that increasing demand, if you think back even 10 years ago about how many screens you typically had in one house, it was typically two. There'd be a computer and a television. Today in most houses there are sometimes a dozen.