DB Question | A hotel reservation scenario

Dear list, e-Greetings! I'm faced with an interesting and challenging problem. Consider a database, designed for a hotel. At any given time, each room has a different status: It's Busy or Reserved, or Free. It's easy to retrieve number of Free rooms at the current time. But how can I count the number of rooms that were busy during the last week ? I would appreciate if you take a brief moment of your time and share your opinion. Thank you in advance, -b