The national average price for regular gas continued to fall on Friday, dropping to $4.391 per gallon, a 16-cent decrease over the past week, according to AAA.

Gas prices have trended downward since setting a high for the year on May 21 at $4.564 per gallon. Moreover, fuel costs have dropped every day this week, starting at $4.507 per gallon on Monday, Memorial Day, dropping to Friday’s current price point, an 11-cent drop in less than 100 hours. The decrease in fuel costs comes at a time when gas prices start to rise, after Memorial Day and the beginning of what is recognized as the summer driving season.