The average price of a gallon of diesel rose 3.2 cents, putting it at 3.208 and a 3-year high. The cost is up nearly 50 cents over a year ago, with a uniform rise across the nation. Barrels of crude are dropping below $64/barrel as the number of U.S. oil rigs rose to 752, over 500 more than last year. Gasoline is rising by around 20 cents, with metropolitan areas expected to reach higher prices most rapidly.