I know how many customers of each customer-size group each sales representative handles on an annual basis. Is it possible to calculate the likely time/effort required by each customer size based on this data set? Or said differently, I'm trying to find out if larger customers require more or less effort than smaller customers.

Is there a function or formula in Excel that will allow be to answer the above based on the data set below?

To add some context, in case it is helpful. There are 2080 work hours a year. I'm assuming they spend all their time with the customers under their responsibility. I also expect that the largest customers require more time than a small customers, but I dont know how much more. That is what I'm trying to figure out. Some employees do handle a lot more customers than others, so its probably best to look a the relative difference between the customer sizes for each employee...

Customer size is rated from 0 (very small) to 7 (the largest).

Below is a small data extract of a large Data table