Indian Population Hits one Billion     The Asian nation of India has reached a milestone surpassed by only one other nation on Earth. India has now joined China as the only members of the one billion club: nations with more than one billion in . No one knows for sure exactly when it happened, although the occasion was marked last month. For many, the one billion mark is not cause for celebration but concern as this already crowded country struggles to make room for more and more people.