Average retail gasoline prices in Michigan have fallen 11.2 cents per gallon in the past week, averaging $3.43 a gallon Sunday. This compares with the national average that has fallen 3.7 cents per gallon in the last week to $3.39 a gallon, according to gasoline price website MichiganGasPrices.com.

Including the change in gas prices in Michigan during the past week, prices Sunday were 15.1 cents per gallon higher than the same day one year ago and are 2.9 cents per gallon higher than a month ago. The national average has decreased 11.3 cents per gallon during the last month and stands 10 cents per gallon higher than this day one year ago.

“While the national average continues to fall, we’ve done the math — the yearly average in 2012 is all but guaranteed to set all time record highs,” said GasBuddy.com Senior Petroleum Analyst Patrick DeHaan. “We still stand at $3.63 a gallon for a yearly average, and gasoline prices would need to average no more than $2.35 a gallon for every day left in 2012 for the national yearly average to drop below 2011, something that appears impossible. In the meanwhile, we have lowered our forecast for Christmas gasoline prices to average between $3.25 to $3.35 a gallon.”