For National Defense Academy (NDA ) examination , there is no such percentage criteria. That is you just need to pass you class 12th exam.
Even Candidates who are appearing in Class 12 or equivalent examination can apply.
The main important Ascepts NDA focus on are Height , Weight , Age , Fitness and vision.
Best Of Luck for your Exam !
There is no minimum percentage you just need to qualify your 10+2 that is 12th by state education board or a university. Please click the below link to know more about the eligibility criteria for NDA