One thing I should explain about a coal-fired generating plant is that over its life it's a real challenge to maintain the actual efficiency of the plant from when it was built, from its design criteria, so you're continuing to do that anyway. We're not basing the CO2 cost on any of those marginal improvements.
I would say the efficiency improvements in coal-fired power plants, generally, are extremely small. If we can get a 0.1% improvement, we're doing well.