Has there been consistency or volatility of total compensation related to profit brought in per employee in the USA?

I thought of this question after looking at the profit metrics of deals I've completed so far this year, and understandably there's other support staff that need to be compensated who don't really generate profit, but I was pretty shocked how little of that money is actually going to me in total compensation (salary/bonus/health insurance). As in less than 5% total.

I also recalled when interviewing for a law firm what their billable expectations were, the $ amount per hour, and that it came out to roughly them paying me around 9% total compensation for what they expected me to bill.

Has there been a trend of the share of compensation related to revenue/profit decreasing for non c suite employees recently?