?s about subletting and bills

[UWOAPhi]

Let's say that there are 6 people renting a house from May to April. 2 have decided to live in the house over the summer, 2 have decided to have subletters live in the house from May to August and 2 have decided not to live in the house until September. What is the fairest way to split up the utilities bills from May to August?

1) Split 20 to 30% of the bills split between the 2 not living in the house and the remaining 70 to 80% split among the 4 living in the house

2) Have the bills split evenly between the 4 living in the house and none charged to those not living in the house

3) Have the bills evenly over all 6

4) Split 50% over all 6, then split the remaining 50% over the 4 living in the house

5) Other?

Any advice regarding this situation would be greatly appreciated.