Custom objects are helpful when you are going to preserve data to use later.
Here as i could understand you need to show results according to some fix values for a fixed time interval. So, It means that your data is not going to be increasing with respect to time. It will always for 6 quarters.
I would recommend to create a visualforce page which will do some calculation by fetching some values from existing object records and show on page in a user-friendly way.
If you think that your requirement can be enhanced in later time and some major functionality can be added on visualforce page then you can design the visualforce apex controller to support custom object when required.
Another thing, using a well designed custom object will solve various complexity on visualforce page design.