Anyone know how to estimate typical duty cycles for a typical refrigeration system to estimate the energy costs?

I’m trying to evaluate the energy savings of placing a VFD on a screw compressor. The VFD salesmen is asking what is the typical duty cycle for evaluation purposes.

Is there a simple way to estimate or long way to calculate how much time a typical screw compressors runs at

100%, 90%, 80%..... ect?

Thanks

Dan Acosta