The BSE started publishing the value of the sensex only from 1985 when it was in the 400-point range. The same year it gave the highest annual returns, 94%, while in 2008 it had more than halved, from over 20,000 to a little over 9,600.

from Times of India https://timesofindia.indiatimes.com/business/india-business/a-rs-1-lakh-investment-in-sensex-in-1979-would-have-risen-to-rs-3-9-crore-today/articleshow/68679119.cms