The marks per year vary, but you need 80/100 UMS average in C1 and 2 (edit: and your applied modules, so M1 and M2), and 90/100 UMS average in C3 and 4.
It's really difficult to say how many marks this will mean per paper. I did one past paper that required 62/72 (85%) for an A, and another that required 54/72 (75%). It also varies wildly for your applied modules, for instance most MEI D1 papers only ask for 57/72 (79%) for an A, and often it's lower than that.