What does a detailed look at immigration statistics tell us about the benefits, or otherwise, of welcoming overseas citizens? Plus, is it true that by the age of 60, more than twice as many women as men are single, and that older men are often living with younger men? Do two large glasses of wine triple your risk of mouth cancer? And which of the world's best tennis players of all time is also the worst-ranked player in one sense. Tim Harford presents.