I was going through Bank of Baorda Q1FY17 presentation. Came across interesing slide about rating of domestic accounts by Bank. While not sure whether same would be case with other Public/Private Bank, it give some indication about potential of 1-2 years growth in BLR for rating industry
http://www.bankofbaroda.com/download/Analyst_Presentation_Q1_FY_2017.pdf (refer to slide 16)
Similarly, find enclosed Bank of India Presetation for March 31 2016 results, providing details about rated accounts:

