Our client's SFMC Contacts count is overage, and before we can perform the contact deletion to reduce the contacts count, we would like to know the contacts count trend over the past 6 months.
I wonder if we have any approaches to find out that.
My very rough idea is using the Mobile filter list workaround to get all subscriber keys in All contacts list, then mapping with
_PushAddress data views to get the CreatedDate field then use it to filter out. However MC contact data model is complex with many layers and not all data views using subscriber key but contact ID for mapping so I am not sure how this idea is going to work.