Chart that shows running total by year

Hi! I'm trying to create a chart that compares the registration totals by number of weeks out (i.e., where are we this year in comparison to this time last year). I created a chart that looks like the one below. The expression is =RunningValue(CountRows(),Sum,Nothing)

The problem is, it displays one running total across all years instead of separating the total by year.


Any idea on how to fix this? I'm spinning my wheels at this point.

Kate
(SQL Newbie)