That's a great question.
The data that we have.... It's eliminated over time, and recognize that these are all around implementation, and so depending on the uptake and depending on how you calculate it, and the timeframe that you take it.... So this becomes a “how long is a piece of string” type of question, because there are a lot of caveats and conditions on how you actually measure your emissions: are you measuring at a point in the year, or are you measuring the net emissions? What we've done is a net present value of these emissions over time, and what is the societal benefit, because people think in dollars and cents, they don't think in tonnes of CO2 necessarily.
When we look on the domestic side, the net benefit from our early investments, which were just several hundred million dollars, show that it's several billion dollars worth of return. So there has been a 14 times, 15 times return on that kind of investment. Those are kind of the figures we're looking at. That's how we do the math on emissions and turn them into a quantifiable economic value.