While motor fuel prices over the past week remained relatively stable, natural gas prices jumped by $.73 per million British thermal unit. The Iowa Department of Agriculture and Land Stewardship is reporting that, as of Wednesday, the price of natural gas at the Henry Hub reporting site is now at $4.64 per MMBtu. The U.S. Energy Information Administration cites a spike in temperatures over the past week throughout the Midwest that drove up demand and prices. As of Sept. 1, AAA Iowa reports the average price of regular unleaded gasoline rose two cents over the past week to $3.01 a gallon, which is $.16 below the national average and $.90 higher than one year ago. Retail diesel prices bumped up by a penny to $3.11, which is $.18 less than the national average and $.87 higher than this time last year. Wholesale ethanol held steady at $2.22 per gallon.