Ravi, if you got 99 out of 200, that is equivalent to 49.5%. Now to be eligible for a seat in IIT, you need to qualify either of the two criteria with respect to your 12th boards performance:

• You need to score at least 75% in your 12th boards. SC/ ST and PWD candidates are given a relaxation of upto 65%
• Else, you need to be in the top 20 percentile of successful candidates in the exam conducted by your respective board.

In your case, you would not be clearing the first criteria. So you need to be in the top 20 percentile of your board. The percentage required to be in the top 20 percentile would be released by the respective boards after declaration of board examination results. Else even if you have AIR 1 in JEE Advanced, you would not get a seat in any of the IITs.