Just what has brought on the latest sharp fall is far from clear.
It ended the day at $115.125, down $12.75, or nearly 10 percent, helping to send the whole market to a sharp fall.
As a result we have seen a sharp fall in the numbers who sleep rough on our streets.
The first and most striking thing about these figures is the sharp fall which they show.
The sharp fall in the number of young drivers has come at a critical time for the insurance industry.
Last year's sharp fall in oil prices added to the problems.
A sharp fall in drug production was the main cause.
A sharp fall in interest rates might, but that looks improbable now.
The economic and financial crisis also brought a sharp fall in world trade.
The increased supply led to a sharp fall in prices.