The price of oil has soared to a new high, hasn't it? A CASUAL observer might be forgiven for thinking that the oil price reached a new record, of $115.07 a barrel, on April 16th. And so it did, in nominal terms. But by other measures, oil is not quite as expensive as it seems. That, in turn, may go some way towards explaining why demand for oil continues to rise in many countries, despite prices that would have been unimaginable just a few years ago. Michael Lewis of Deutsche Bank has come up with several different ways of comparing past and present oil prices. The first step is to account for inflation. But what measure of inflation is most suitable? If historic prices are inflated in line with America's producer-price index, the previous record, struck in the early 1980s, would be the equivalent of $94 in today's money