Function Logic

[Tincupjr]

Here is a problem I could really use help with. My new company I have joined does not believe in using computers. Everything is paper and pencil to which I like in some respects but in others it sure is nice to have a machine to work it for you.

My issue is: we track sales by the hour for each hour of the day from 10am until 11pm each day. The data goes back about 36 weeks to which I am prepared to enter into an excel spreadsheet to start working with the numbers.

Here is the help I need... I would like to enter the current data on line 5 each time for each cell for each hour going horizontally and just insert a line there to move the older data down as time goes by. Now, I would like on line 3 to give me an average of all the data going downward in the column. That is the easy part. My question is: can I put a formula or function in Line 3 that would update with the average of the column but would automatically update the equation the additional line added at the bottom or the top? My line 5 would be consistent but as time goes by weekly, following weeks data would be moved down one row to which the bottom line would increase as more data was entered.

Any ideas as to how I could make this work?

Thanks,
Joe