Over the last five weeks, the national average price has dropped 21.9 cents.
Over the last four weeks, the national price has dropped 18.2 cents. The latest price is 58 cents higher than a year earlier.
The energy department forecast crude oil will average $102 a barrel next year.
Over the last three weeks, the national price has dropped 11.6 cents.
The price for the week ended Dec. 5 fell 3.3 cents to $3.931.
The U.S. average diesel price dropped below $4 a gallon.
Price crossed a notable threshold by exceeding $4 a gallon for the first time since mid-May.
Since Oct. 10, the national average price of diesel has climbed 26.6 cents a gallon.
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