Hi! I have a problem related to filtering and donno whether AS and Excel can help me to finish the job

I would like to create an OLAP cube and then export the resul to Excel as a pivot table. I would like to build a dimension which can help me to filter the items which sales are less than X% of the total sales. In other word, the pivot table only shows the items which sales are over (100-X)% of the total sales. Of course, I can choose X in dimension

What things should I do in AS or Excel, so that I can get the above result

Thank you

Jessica