Multiple columns in pivot table

[TeacherInNeed]

Hi

I am a teacher trying to analyse a whole school round of assessments. I have a table with a complete year group with a 'score' of between -5 and 5 in subject columns. If a student doesn't do a subject that cell is blank. I've managed to build subject specific pivots but when I add further progress scores into columns I get all sorts of weird. I just want total counts of specific grades for lots of columns.

Thanks in advance and sorry if I've missed this elsewhere.