National Fuel Gas Distribution Corporation (National Fuel) has submitted to the Pennsylvania Public Utility Commission its quarterly adjustment to gas supply charges. This adjustment decreases the monthly bill of a typical residential customer using 94,900 cubic feet of gas annually by $4.91 from $58.48 to $53.57. This 8.4 percent decrease became effective Feb. 1, 2016. National Fuel says the main driver of the decrease is low market prices due in large part to the increasing production of Marcellus Shale gas. Nearly all of the gas consumed by National Fuel utility customers comes from Northeast-produced shale gas.