Hello!
For my project, I need to create a new column that calculates a weigthed average yearly. The problem is, sometimes I only need to start the yearly average from a certain month (for example, May in the third row of my example), or end at a certain month, or take only certain months between some dates into consideration (like the 4th row of my example). "Not Available" means that there's no start/end month, so I take all months into the calculation.
How can I reference certain columns to include in my average, based on the input of Start/End month?
