I have a line chart that is tracking a percentage over time. It also has a filter for 50 different clients. I would like to create a threshold that is based on a portion of the date range. As I understand it, this would be done by adding a column to the data that populates with an if statement on the date. The issue is that the date range in use would be different for each client.

Is there any methodology to get this working short of individual reports for each client?