See how a running total of parcels differs from a rate of change: one tells how...

https://articlegrovey.com/s/Ph1A9YQDptH7i2wWa4zZ1

See how a running total of parcels differs from a rate of change: one tells how many have arrived so far, the other how many arrive per hour. The article uses clear units and time windows to make both numbers useful in a shift report.