Filtering data from the results of a sumifs formula

Hi, question for anyone out there. After a long search I have not been able to find an answer. I have two sheets in an Excel document, one containing a bunch of data, the other sheet summarizes the results. On the summary tab, I have four sumifs formulae:

=SUMIFS(Data!I:I,Data!P:P,"1",Data!R:R,"A")
=SUMIFS(Data!I:I,Data!P:P,"1",Data!R:R,"B")
=SUMIFS(Data!I:I,Data!P:P,"1",Data!R:R,"C")
=SUMIFS(Data!I:I,Data!P:P,"1",Data!R:R,"D")

It is basically summing if a sale is made in January (month 1) and commission category A, B, C or D. That part has worked fine so far.

What I want to do now, is filter these results by salesperson, which are listed in Column L of the data tab. Ideally, I would like to have a drop down box with all the salespeople listed there, and the sumifs formulae would reflect just each individual. As right now, they reflect all the salespeople as a whole. I tried to input an advanced filter, but nothing was working for me.

Any thoughts or ideas would be greatly appreciated.

Thanks!!

Try to solve it with a PivotTable