Dynamically weighted Identical tables

Hi All, 

I have a report that is self serve to others. They pull it as a PDF so it has too fit the screen.

We have two identical tables which present as students Assessment Marks 

We have weighted it using Surname A-M on left and M- Z on the right. But can be very heavy to one side if too many fall on either side of the alphabet. 

my question is how can I dynamically rank a table so they have equal amounts on each side, after the user selects which "employer" they want the rpeort for. Doesnt need to be alphabetical, just equal amounts