For decades now, politicians have been able to tell us we are getting richer. From the West to China and beyond, the whole world dreamt of becoming home owners, car owners and holiday makers. And the promise made sense, because the economic growth rate across the world kept on climbing. Many people assumed this growth would return quickly after the 2008 crash - but eight years on, it remains low. This week's edition asks: why is this happening? And is this lack of growth now permanent?