As expected, Opec rolled over its oil-production quotas at its meeting in Vienna today. With oil futures trading at over $100 a barrel, consuming countries such as the US had lobbied the producer group to release more oil onto the market. That, though, was always unlikely: oil demand experiences a seasonal dip going into the second quarter and Opec is usually inclined to cut production to shore up prices at this time of year. The cartel has also repeatedly underlined its fears that wobbles in the US economy will soon feed through into lower oil demand.