Moving Average as a Line Value in Combo Chart

Hello,

I am trying to create and display a dynamic average for a measure and input it in as a line value.



I already had created a new measure titled WinRate  --> WinRate = Divide([NumberofSales],[NumberofBids])

What would be the DAX expression to calculate the average for the new measure and input it into the "Line Value"?  Any help would be great.  Thanks!