The law of supply and demand would predict that an increase in gasoline prices would lead in the long run to an increase in the average fuel economy of the U.S. passenger car fleet, and that a drop in gasoline prices would be associated with a reduction in the average fuel economy of the entire U.S. fleet. There is some evidence that this happened with an increase in market share of lower fuel economy light trucks and SUVs and decline in passenger car sales, as a percentage of total fleet sales, as car buying trends changed during the 1990s, the impact of which is not reflected in this chart.