I believe the rule of thumb I've heard is about 20%. I know that Hans Konow is going to be a witness, and he's nodding. Subsequently he may be able to shed some more light on this, but 20% as a rule of thumb would be a more comfortable margin for most of the utilities; 25% is getting a little bit high, as a result of overbuilding in the past, but I think 15% is probably getting a little bit tight for what people would be most comfortable with.
On April 16th, 2007. See this statement in context.