I don't quite get it. What is this data based on? What goods are included?

The price of food, for instance, has fallen dramatically just in the past 50-75 years. In both percent-of-household-budget and real dollar terms, it's dirt cheap compared to what it used to be. So any CPI-type "basket" that includes food ought to show price deflation over time.

In the meantime, many things that would have been unthinkable luxuries have become regarded as necessities of one sort or another. I suspect the average number of square feet of living space has gone up dramatically, as has energy consumption. But to just factor that into "price" doesn't seem particularly fair, since the 'average' standard of living in 2005 is so much higher than in 1795.

The chart is neat but it needs more context.