Aside from short-lived booms in the 1990s and 2000s, US productivity growth has averaged just 1.2% from 1975 up to today after peaking above 3% in 1972.

As we detailed previously, adjusting for the WWII anomaly (which tells us that GDP is not a good measure of a country’s prosperity) US productivity growth peaked in 1972 – incidentally the year after Nixon took the US off gold.

The productivity decline witnessed ever since is unprecedented. Despite the short lived boom of the 1990s US productivity growth only average 1.2 per cent from 1975 up to today.

If we isolate the last 15 years US productivity growth is on par with what an agrarian slave economy was able to achieve 200 years ago.

As we reported last year, users spent 51% of their total internet time on mobile devices, for a total of 5.6 hours per day snapchatting, face-booking, insta-graming and taking selfies.

It's an everyday sight - people using their phones while sitting on the train, waiting for a bus, or even having a meal with their partner.

What exactly are they doing the whole time though?

When it comes to social networks, Verto Analytics may have the answer. The most time spent in the U.S. on a 'mainstream' app is the 899 minutes per month of the average Facebook user.

The social network whose users invest the most time though is a networking app for gay, bi, and curious men - Grindr. WIth a huge 1,040 minutes on average, that's over 17 hours every month.

In third place, Growlr is also a networking/dating app for homosexual men. The average user here spends 665 minutes per month.

In eighth, Twitter's struggles are again highlighted, with only 176 minutes in Q3 2017.

Figures refer to usage across all platforms, not just mobile.

You will find more statistics at Statista

So, maybe in their next wide-ranging study, economists could include a test group of workers who leave their phones in a locker at the beginning of the work day, and try to measure how much their “productivity” improves. So, while every effort can be made by Ivory Tower academics to solve the problem of American worker productivity, perhaps it can be summed up simply as "Put The Smart-Phone Down!"