It seems like I'm always looking for this graph comparing the adoption rates of different technologies (cars, microwaves, color TVs, cellphones, etc.). No more...it's posted here for my future reference.
The referring article on the differences between what people spend and what people earn is worth noting as well.
If we compare the incomes of the top and bottom fifths, we see a ratio of 15 to 1. If we turn to consumption, the gap declines to around 4 to 1. A similar narrowing takes place throughout all levels of income distribution. The middle 20 percent of families had incomes more than four times the bottom fifth. Yet their edge in consumption fell to about 2 to 1.