hello bivas..,

the present evaluation of nta, the percentile isnt actually dependent on the jee score or marks you get, it is the factor of hardness of the question paper of that sesssion and the number of students wrote the exam on that particular session that matters for the percentile. the percentile score may vary according to these factors. by the way if you score a mark of 120 in one session of jee whereas some other scored a mark of 200 in another session, there can be no assurance that the second student gets the higher percentile, it can be the first student who may get the higher percentile if the paper of that session was tough and the average lies below the score he or she obtained.

hope you understand..

all the best