"We have, therefore, only one choice left to arrive at a tentative percentage of Muslims in A.D. 1600... by 1600 Muslim numbers may not have risen beyond 15 million. In that year the total population of India has been estimated at 140 millions. Muslims would have formed about one-ninth to one-tenth of India’s total population."
January 1, 1970
https://en.wikiquote.org/wiki/Demographics_of_India