You could imagine measuring in terms of each customer's annual incomes. In a year, you might provide value corresponding to 1% of ten customers' annual incomes, or you might provide value corresponding to 1% of a thousand customers' annual incomes. In some sense, in the former case you created a tenth of a person-income of value, whereas in the latter you created a hundred person-incomes worth of value. It'd be an interesting measure.

It would be difficult to make meaningful for a large group because a transfer from A --> B --> C --> D won't measure the same as a transfer from A --> C --> B --> D even though the outcome is equivalent.