I'd be very surprised if it was only 20%. By my estimation many office jobs are 50% or more just being paid to sit at a desk.

And the less well paid jobs (eg Veterinary Assistant - not technician or McDonald's employee) have individuals working near constantly. There is a class divide under the 1% which is also quite stark, with regard to work demands.

I think I've witnessed that fraction go up when raises and promotions fail to meet expectations.