I doubt you have any source, because no reputable one would mash together all types of industries into one stat.
For example, the service industries pay a high percentage of revenue out as payroll. Manufacturing sectors pay a low percentage. In between is retail.
What determines the percentage is the complexity of inventories. In declining order of types of inventories, the industries are manufacturing, retail, and with no inventories to speak of, service.
To be more accurate, you'd have to classify industries more finely than just the three broad categories I used.
Anyway, it's interesting that you want government employees to be socialist altruists after giving up their high pay in private management. And you want private headhunters to ignore talent developed in government and not hire them away. That's the only way to keep top government employees low-paid.
I'd like to see both sides, top people in private and government, paid less. The economy is dying because consumers overspend on both sides, giving away trillions on rich people's tax cuts.