How did you measure that?
What you fail to understand is that there only a certain amount of cheap oil we can extract from the earth and reserves of that oil is decreasing and its becoming harder to extract since we are running out of it.
Its extremely costy to extract every bit of oil from earth\'s deeper layers and thats not the same as the oil we have been extracting and proccesing.
Its costly inneficient, productiively inneficient, more time consuming that there is no point.
And the oil we know now didnt take only centuries to have the form we are using. We are talking about millions of years.
Earth is not a factory that produces oil on our demand.Our demand is increasing more than the supply.Thats why the price increase.
Its ecomonics.
Also read this
http://www.hubbertpeak.com/services/proposal.htm