Assuming your query is related to NITs & IITs so for this year the top 20 percentile is not yet out but to get a rough idea you can go through the below previous year trend -
https://josaa.nic.in/webinfocms/Handler/FileHandler.ashx?i=File&ii=86&iii=Y
https://josaa.nic.in/webinfocms/Handler/FileHandler.ashx?i=File&ii=87&iii=Y
Good Luck!!!
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