Why are diesel fuel prices higher than gasoline prices?

I continue to have trouble remembering why this is (even after seeing or hearing it explained to me several times... an "adult moment"?)... From the Energy Information Administration:

Until several years ago, the average price of diesel fuel was usually lower than the average price of gasoline. In some winters when the demand for distillate heating oil was high, the price of diesel fuel rose above the gasoline price. Since September 2004, the price of diesel fuel has been generally higher than the price of regular gasoline all year round for several reasons. Worldwide demand for diesel fuel and other distillate fuel oils has been increasing steadily, with strong demand in China, Europe, and the U.S., putting more pressure on the tight global refining capacity. In the U.S., the transition to low-sulfur diesel fuel has affected diesel fuel production and distribution costs. Also, the Federal excise tax on diesel fuel is 6 cents higher per gallon (24.4 cents per gallon) than the tax on gasoline.

It's all about supply and demand. Go figure.