We use Normal rainfall at an area as a standard for comparison purposes. When was the Normal rainfall  last calculated ( by IMD, I suppose) in India? What period does it include? I mean which decades? How many normals ( for rainfall) were calculated in India by IMD since 1901?
I would appreciate knowing the source of information also for this answer.
Thanks for for this opportunity to share my doubts.

Subramanya,

subramanyak1@gmail.com