Just remember that they count the mark gaps between ranks as well. So if the gap between you and 1st place isn't too big, it doesn't necessarily mean you will get the 22nd best mark.
For example, if someone was 2nd in a subject with a gap of 1% from 1st place in school assessments and the top two marks in the HSC exam ended up being 95 and 90, then 2nd place would most likely get an internal mark of 94 rather than 90.