In
Oil 101 I describe how oil demand evolves. As you can see from the chart below (from Chapter 1 -
Oil 101), oil demand is initially strongly correlated with GDP. Then when oil demand gets to a certain level it tends to level off in per capita terms. In 1985, 24.45 barrels were consumed by the average US person. In 2008, the US average was 23.3 barrels even though population size and the economy had changed significantly.
Page 18, Fig. 1-13, Morgan Downey, 2009, Oil 101