Hello aspirant, 

Percentile is calculated according to the top score in the exam

Percentile =(your score÷top score) *100

And as if now top score not yet released so please wait till the end of this month  and previously it is only one exam and now two exams and best of one will be taken by nta

Hope above information is helpful to you 

If you have any queries please let me know 

Thank you