An old thread - but in case anyone lands here looking for similar data, as I did - JH now publishes the full details of each annual set of tests - by grade, by sex, by number of takers, mean, median, SD, etc., along with a table of the actual number of takers at each score, and the percentile with that score.

This answers the question of how someone did relative to all of the students who took the same test, vs. the percentile within a 2-5 year older set of students.

Latest, for 2014, is here - http://cty.jhu.edu/talent/docs/test%20data%20scat/2014SCAT.pdf

Replace 2014 with the year, back to 2010, to get prior data.