In macroeconomics, there’s a rather tired old saying: “Demographics is destiny.”

The idea is simple. If your workforce can count on the young, the marginalised or immigrants joining in greater number than those leaving it, your economy is in a pretty sweet spot. Consumption, investment and tax revenue should naturally edge higher. Think of the UK in the 1980s, when women began entering the workforce at an accelerated pace. Or the USA’s long-lasting ability, up until recently at least, to attract people from all over the world.

Conversely, an ageing population is a major drag. Not only as your workforce is shrinking, weighing on growth, but as those retirees need their care and pensions funded by a smaller and smaller pot of taxes. Japan, whose population has been in decline since 2007, is the most notable example of this.