Unconscionable Stamp Gouging?

The graph above (click to enlarge) shows a 50-year history of the real price of gasoline (using these EIA data) from 1957-2007 and the real price of a first-class U.S. postage stamp (using these data and the same price index from the EIA to adjust for inflation). Both prices are expressed as an index that has a value of 100 in 1957.

As the graph shows, the real price of gas today is only about 20% higher than it was in 1957, even though real per-capita disposable income is about 3 times higher today. Compared to the peak in 1980-1981, real gas prices are still about 12% lower in 2007.

In contrast, the real price of a first-class stamp has almost doubled in the last 50 years, and is now almost 90% higher today than in 1957, and had more than doubled in price in the mid-1970s.

Granted, the real price of a stamp has remained relatively stable over the last 20 years, which is why we probably haven't heard a lot complaints about "unconscionable stamp gouging." But over the last half-century, isnt' the case for "unconscionable stamp gouging" is a lot stronger than the case for "unconscionable gas gouging?"