According to this rediff article the ratio this year (2007) is around 1 or 2 final calls in IIMA and IIMB from 80 applicants who received a call based on their GMAT scores.

The ratio this year (2007) is around 2 final calls from 14 applicants who received a call based on their GMAT scores in IIML Similarly 2 or 3 NRIs have gotten into IIMK.

As for GMAT cutoff scores for IIMs while IIM-Lucknow has clarified that its GMAT cut-off score is above 85 percentile rank, the other IIMs do not have fixed cut-offs but say that they accept only those students who have a score of above 750. In fact IIM-Ahmedabad's Post Graduate Programme in Management for Executives (PGPX), which accepts only GMAT scores to encourage foreign nationals has a much lower cut off at 699.