Averages by time period and cumulative for averages

Hello, I am trying to calculate averages for selected periods and cumulative totals for those averages. No issues calculating Cumulative total per period for Actuals Quantity.

Actuals Cumulative Total = CALCULATE (DemandAttainment_Sales[Actuals Quantity],

FILTER (ALLSELECTED(Date_Dim),

Date_Dim[Date] <= max(Date_Dim[Date])  ))

But cannot find a way to calculate averages for Current Plan Demand and Cumulative Total for calculated averages (highlighted in the data pic below).  My visual and data should look like that:

Any help is greatly appreciated

t