AAS students which.havejust about 37% students, submit assignments on time

You seem to be saying that AAS students are not completely AAS students – 63% of each AAS student is not an AAS student!?

Perhaps you mean:

*AAS students,*.**who represent**just about 37%**of all students**, submit assignments on time

You are much more likely to make sense if you construct a noun phrase in which your percentage number is followed by ‘of’:

x% + of + ‘the whole’^{(???)} + verb + etc.

Make sure you state * the whole* explicitly. For example if you are discussing male and female representation among students, then the ‘whole’ is

*students*. If you want to say that

*50% of students are female*, do not write

*50% of females are students*. For a more detailed look at what I mean by the ‘whole’, take a look at my post Don’t forget the whole.

Use this structure with the first two or three numbers that apply to each new theme that you introduce and your reader will understand what the numbers refer to. You will also receive a good score in IELTS in all four assessment criteria (see public band descriptors).