ANOTHER 22 CENT DROP IN REGULAR UNLEADED PRICES IN IOWA, ACCORDING TO THE WEEKLY FUEL SURVEY FROM THE DEPARTMENT OF AGRICULTURE.  A GALLON OF REGULAR UNLEADED NOW AVERAGES $4.24, STILL $1.25 HIGHER THAN AT THIS TIME A YEAR AGO.  NATIONALLY, A GALLON OF REGULAR UNLEADED AVERAGES $4.47, DOWN 16 CENTS FROM A WEEK AGO.  DIESEL PRICES IN IOWA A YEAR AGO WERE AT $3.12 A GALLON.  THE CURRENT AVERAGE IS $5.16, AN 11 CENT DROP FROM A WEEK AGO.