Carry trade

When you are given a series of rates… 6 months, 1 year, 2 year, 3 year.

To determine the return, you subtract 6 month rate from 3 year rate, and then divide by 2.

Why do you divide by 2? Is it because they give you 6 month rate?

If the rates given are 1 year, 2 year, 3 year, 4 year. Do you not divide by 2 in this situation?

I guess numbers in the table are annualized returns and they want to find 6 month return.

Unless otherwise stated, bonds pay coupons semiannually.