I'd say probably top 25 % in each subject, but you want people like 'aysce' to answer your query as he is precise.
By no means am I precise haha, no estimate is to be frank but you can get a general feel of what someone's going to get I guess.
English Advanced x/273
General Maths x/137
Ancient History x/67
Business Studies x/99
Design and Technology x/25
Imo,
English Advanced ~40-45/273
General Maths ~30-40ish/137
Ancient History ~15/67
Business Studies ~20-25/99
Design and Technology ~10/25
I may be completely off but I think if you get these ranks, you'll be able to achieve 90+.