Gasoline prices in Iowa have jumped up more than a dime a gallon in the past month. Dawn Duffy, spokeswoman for Triple-A Iowa, says it’s typical for the wintertime to see that sort of bounce. The current statewide average is a dollar-85, up from a dollar-74 last month and way up from a year ago when the price was a dollar-57. Duffy says several factors are coming into play in making the pump prices rise. February is usually when the oil industry shifts its focus from heating oil production to gasoline. Inventories of gas are higher than normal now but demand is also up, keeping us about even with where we were a year ago. The calendar says spring will arrive March 20th — just over a month away — which Duffy says may boost demand even higher, along with the prices. She says it’ll be a time to keep an eye on gas prices to look for the lowest prices available.According to the Triple-A survey, Davenport has the most expensive gas in the state, averaging a dollar-88 while Des Moines has the cheapest at a dollar-79.