It changes each year depending on the difficulty of the papers.
English Advanced - 76-82/100 (Around 77% to 80% last year depending on prescribed texts)
Chemistry - 72-76/100 (72 last year)
Mathematics Extension One - 56-58/84
Mathematics Extension Two - 74-77/120
Guy above - paper 1 is 40% and paper 2 is 60% so the mark for English is out of 100 not 105