If you want to show a rolling average and its constituent parts in a bar chart (which might be what you are getting at …), if there are not many bars you can just use different expressions for each piece, similar to the below (I've stopped at the 3 bars as just an example);
There are things that can be done to improve the display (e.g. change bar colours, get text on the axis). The set analysis used to get the dates should also be dynamic, but getting into that really depends on your data model & if this is even what you are trying to do.