I'm not exactly sure what you're looking for here, but if you take your Change... pill off the level of detail, and then convert it to a dimension, then change it to 'continuous' (green), then put it back on the level of detail shelf and recreate the reference line using a simple sum, then you'll get the totals I think you're looking for. (Miss any of these steps, and the Change... field won't be available in the reference line box.) See attached.
Hope this gets you going in the right direction.
Thank you - that worked perfectly!!!