I want to record the percentage change of a value from one week to another.

For example: I deal with a client who brings in 10€ is week 1. In week 2, he brings in 30€. The percentage change is a 300% increase.

Say there's another client I hadn't yet dealt with in week 1, but am now working with him in week 2 and he brings 1000€.

What would be the best way to represent this new client's change coming in? I could say it is 100%, but that somehow does not seem reflective of the true value of this client. Indeed, had he brought in 10€ in week 1, like client 1, the % increase would have been 10,000%, and thus should be much more valuable than client 1.

Can I simply replace the 0 in week 1 with a 1? Or should I do the actual amount as the percentage increase or 100 times the new amount (1000, or 10,000). What is the best course of action?

Thanks