Find Average Progress of Student Form exams

Nov 2016

I would highly appreciate for the solution for my following problem.

I have class of 30 Students and I have taken total 6 exam through out the year.
I have exam mark of the each student for each exam (Note : each exam has different Total Marks)

I want to know whether all over performance of my class is being progressive or regressive based on students performance from each exam result.

What is the Mathematical formula or solution to find this expected result ?

Note : Exam Level can be Tough or it could be very Easy, so achieved % might not give exact idea whether X particular student has got progress or not.