The clearest evidence of hard capacity constraints is probably on the export side. In some parts of the resource sector there was a significant volume of investment in the second half of the 1990s, but a subsequent period of weak commodity prices saw investment decline to very low levels.
Hence, the increase in demand in the past two years apparently left some producers without the capacity to take full advantage of the conditions by shipping higher output, though of course they have enjoyed higher prices. The rise in prices presumably reflects pressure on capacity globally, which suggests that producers everywhere were surprised.