Sources

1074. “Zoroastrianism.” Hinnells, John R. (ed.), Penguin Dictionary of Religions (London: Penguin Books). "The main centres of Zoroastrianism nowadays are India (mainly Bombay), 72,000; Iran, 30,000 plus; Pakistan, 2,000; Britain, 5,000; and North American (USA and Canada), 6,000 (all figures are approximate)."