Again, I would have a hard time commenting on what happens in refined-product markets.
I think this is instrumented in the natural gas industry. The key there is that natural gas is traded in highly competitive markets, where you have liquid trading hubs. One of the biggest North American trading hubs is at Dawn in southwestern Ontario; others are in Chicago, in Henry Hub in Louisiana, or at AECO in Alberta. Those liquid trading hubs--lots of pipe, lots of storage, lots of physical gas available--create opportunities for people to buy and sell gas. And if you look over the last fifteen or so years, it has been a very competitive market.
So it's about infrastructure and it's about transparent markets.