Trailing twelve months pivot chart with calculations

I'm not even sure I can properly explain in writing what it is that I'm trying to accomplish but here it goes. I have a set of raw sales data for a bunch of competitors in my industry. Pretty simple. Column A is the date of each sale transaction, column C is the name of the sales person, column I is the amount of the sale. I want to create a pivot line chart that will give me the trailing twelve month market share for each sales person over a period of time and I do not know where to get started. To make it even more complicated, I want the chart to display only data from the top 5 sales persons, not for every sales person in the database. Any help will be appreciated. I've attached my workbook.

Thanks,

Phil

Hi not sure if i have understood you correctly... however I have added a new sheet to your file with what I think you need... please let me know if this what you need / don't need...

Statistiques Compétition.xlsx

wow that sounds really hard... If i can figure something out with my limited knowledge i will get back to you....