Who's fixing the oil prices?

I've been listening to the arguments on the price of oil.Some say speculator driven,some say supply and demand.World oil consumption is roughly 85 million barrels a day.In August of 2007 the price of crude was around $70 per barrel.It more than doubled to $147.27 on July 11,2008.It dropped over 70% to less than $40 per barrel in December 2008.Those are some extreme swings in prices when demand only fluctuates by 1-2%.So,up over 100%,down over 70%,all from demand fluctuations of less than 2%?I don't think supply and demand tells the whole story,do you?More to come...