60 to 70% of the Pepsi I purchase from grocery stores is flat when I open it. If not fixed I will stop buying Pepsi. Please fix the fizz. The reason I like Pepsi is the carbonation factor. Some of the Pepsi purchased at fast food chains is fine. The store bought Diet Pepsi in 8 pack package is the one I purchase and continuously is nearly flat when I open the bottles. What is the problem is it defective packaging by Pepsi or caused by shaking while being delivered to stores and displayed. Please fix the problem. Thanks for your attention.