Percentage for units going to buffer process nodes

Hi

In this case, the units go from a feeder to a process node, The unit will go to buffer process node if destination process node is not available. I would like to see the percentage of units going to the buffer process node. Is there any solution/feature support what I descripted above?

My current idea is to use switch feature in the process statement, but not sure what variable should I use.

Buffer Percentage.vcmx (232.2 KB)