What is the best way for a couple to share mortgage payments?

Eg one person is earning £20000 before tax and the other is earning £100000 before tax. who should pay what?
Answer
Suze orbloke says the only fair way to split bills when one makes a significant amt. more is you each put a % of your pay into the checking acct. you cannot split the bills 50/50 because the person making less will be struggling to survive. either that or you live within the means of the person who makes less.