How long did it take for a letter to get to the U. S. six years ago?

W: I want to mail this letter overseas.
M: Ok, Ma’am. I’ll have to weigh it first. All right, it’s not overweight. That’s 5.5 yuan for overseas mail.
M: That’s not expensive. How long does it take for a letter to get to the U. S. ?
W: It all depends. It usually takes four or five days.
M: That’s wonderful. It used to take more than a week when I was staying here six years ago. Well, I want to register it.
W: All right. It’ll probably take a little longer to get there though.
M: Yes, I know. Well, please let rile have a post office box.
W: That’s OK. Fill out this form, please.
M: How much is the rent per month?
W: It’s 100 yuan per year.
M: Here is the form and money.
W: OK. Here is the key for you. The number is on it. Any more requests?
M: No, thank you.