In Le Havre, when there is insufficient food during the harvest phase, how is the interest penalty for forced loans applied?

In Teacher Crow's masterpiece "Le Havre": at the end of a round, you need to pay high rations for your workers; if even the grain and dried fish in the warehouse have been eaten up. The rules mandate issuing Loan cards. How much interest must be forcibly paid on each Loan in subsequent rounds? How many points are deducted for each unpaid Loan at the end of the game?