@alan the other approach is bavk-of-the-envelope. If we assume 60 million customers getting hair done 4 times a year and taking 20 minutes, we get 80 million person hours or roughly 50,000 FTEs. Obviously very conservative values, but given most salons are sole traders it gives a reasonable approximation.

I'm now going to have to get my hair cut so I can interrogate my hairdresser about her customer mix.