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Last year the average U.S. household spent just under $3,000 on gasoline, or about 4 percent of its income, according to the Energy Information Administration. With the exception of 2008, when oil peaked at $144 a barrel, that’s the highest share of income that’s gone to gasoline since the early 1980s, when it was closer to 5 percent.

If that seems high to you, remember the U.S. is on the lower end of the spectrum in terms of how much gasoline costs relative to income. In much of Western Europe, a gallon of gasoline accounts for about 6 percent of daily income. In China, it takes about 30 percent of an average day’s wage to buy a gallon of gasoline. Relative to income,...