Diesel prices fell just below $2.50 per gallon this week, dropping 2.4 cents to $2.493, according to the most recent data from the Energy Information Administration (EIA).This week’s price is $1.285 per gallon cheaper than the same week last year, EIA said. Diesel dipped in every region this week – with all regions under the $3-per-gallon mark. The most significant drop was a 4-cent decrease in New England.Average U.S. retail pump prices for gasoline were also down, slipping 4.8 cents to $2.327 from last week’s $2.375, according to EIA. That is $1.026-per-gallon less than the same week last year. Overall, gas prices are down across the board, with the most significant drop in the West Coast – down 8.1 cents to $2.911. All regions remain under the $3-per-gallon mark.According to EIA, U.S. inventories of propane and propylene reached 97.7 million barrels as of Sept. 11. That is the highest level in the 22 years that EIA has collected weekly propane inventory statistics. In the past year, nearly all of the increases in inventories occurred in the Gulf Coast region, EIA said. In the U.S., propane is mainly used for space heating and as a feedstock for petrochemical plants, as well as for drying agricultural crops, according to EIA. The agency mentioned that relatively small amounts of propane are used for fueling vehicles.