Excel 2007 : Creating Pivot for Average

Hello,

I am trying to create a Pivot table to calculate my teams AHT(average handle time) and have a common location to access day wise, week wise and monthly numbers.

The numbers that I recieve from the automated systems already gives out the Acutal AHT, hence while creating the pivot, the Average of Average is being taken which is incorrect as AHT is already an Average number.

I am attaching a sample data, if anyone can help with this would be greatly appreciated.

Formula to calculate the Agent wise AHT

=sumproduct(Chats handled*AHT)/Sum(chats handled)