It is for 1971 data because that is when India had its last reapprortionment. And the reason why they have not done so is to encourage Indian states to support population control. Or else each state will view growing is population as the way to get more political power for itself. For example, Uttar Pradesh and Bihar are underrepresented in Indian politics significantly because of this.
I know that.
I vainly searched for an article on Indian presidential elections per se (as opposed to individual ones) on wikipedia... didn't think of that article title.
