Defect Aging Report in Excel 2010

Appreciate if the Excel gurus can help me with this Aging Report.

I need to create a defect Summary Report, where I can group the Open defects by 'Week' based on the 'Created date'.

The Categorization I want is in the lines of ..

<7 days -- 0 Weeks
>= 7 days --- 1 Week
>7 and <=14 days -- 2 Weeks
>14 and <=21 days -- 3 Weeks.. and so on... upto 15 Weeks

Is there an easy way to accomplish this in Excel ? Any specific formulas that can undertake this task smoothly ?

I'm attaching the file for your perusal. Thanks