There are more constraints than that on a system. For instance, the insurance market only operates up to $1 million. I know that sounds like a lot for a house, but in certain markets it is not. The other thing is that if we're faced with a choice like that, which way will people go? The data suggests contrary to your presumption, which is that a lot more people were trying to have larger down payments, it has more to do with their ability to qualify for rather expensive houses.
It's very hard to know exactly what's going on, but we have a really big cluster of people at 79% mortgages, so they've just made the 20.5% or the 21% down payment. Some people are highly motivated to do the opposite of what you say, but then of course we have lots of people who are also at the other end. I guess that tells us it's a pretty personal choice.