Count new and existing customers

[Rick_T]

Hello all, I am looking for a way to count new en existing customers. I would like to do this per month and per year seperately. So how many new customers do I have this month compared to previous months, and how many new customers do I have this year compared to previous years? 

I work with the following data and corresponding columns: 

[Rick_T]

I figured out the following: 

 =Count( distinct{$<[Faktuurdatum.autoCalendar.Year]={$(=Year(Today()))}>}[Debiteur-nr-Debiteurnr])

Where [Faktuurdatum] = order date and [Debiteur-nr-Debiteurnr] = customer id. 

This returns the customers who placed an order in this year. The expression does not look if it is the first time ever the customer has ordered. 

Does anyone have any tips or tricks? 

It would be very much appriciated! 🙂