I am reading The Ultimate Resource 2 by Julian L. Simon (Princeton, 1996). He makes the point that commodities prices tend to decline over the course of the last couple of hundred years compared to the cost of human labor. The average US wage in 1999 dollars is growing at about 2.1% per year geometric mean from 1900-1999. The real interest rate has been about 1% (in the UK anyway).

This means that if technology were constant and reserves were constant, the real price of a commodity would rise 1%. Otherwise, it would make sense to mine as much oil as possible and put the money in the bank, or leave the oil in the ground and wait for the price to rise.

In fact from 1860-2000 the price of kerosene (see figure 5) has dropped about a factor of 6. If you look at the service kerosene was providing (lighting), it has dropped a factor of 40 from