They call it the Big Quit. Americans are quitting their jobs in higher numbers than at any point since the turn of the millennium. Much has been written about the reasons, from burnout during the pandemic to a “great re-evaluation” of what people want from their jobs.

But this isn’t just an interesting sociological phenomenon. It is also a hard-headed economic indicator with an under-appreciated bearing on pay and productivity. The recent spate of job quitting has to be seen in context: for the past decade, people haven’t been doing anywhere near enough of it.

The proportion of workers who quit their jobs (which Nicholas Colas, co-founder of DataTrek Research calls the “Take This Job and Shove It” index) usually moves in tandem with the health of the labour market. People are more likely to leave for something better when opportunities are plentiful and to cling to their current jobs when unemployment is high.