How can I re-base monthly financial time series I have a monthly time series with 2015=100. I want it to be in 2010=100. How could I do so?
It is from 195901 to 201407.
I have a monthly time series with 2015=100. I want it to be in
  2010=100. How could I do so?


Unless I am misunderstanding your question, you need to multiply every entry by $$100/X_{2010}$$