In an article published by the Times of India on 17 April 2017, Ravi Shankar Prasad, the Minister of Electronics and Information Technology, wrote: "According to our estimates Aadhaar has saved approximately over Rs 49,000 crore in two and half years by eliminating crores of ghost beneficiaries in programmes like MGNREGS, Pahal, schools, PDS." Please provide a full and true copy of any documents that mention this estimate or provide the basis for calculating this total.