If Mr. Guzzler spent $2.99 per gallon for 18 gallons in week 1, $3.09 per gallon for 15 gallons in week 2, $3.29 per gallon for 12 gallons in week 3, and $3.59 per gallon for 10 gallons in week 4, what was his average cost per gallon for the four week period. Express your answer to the nearest cent.