Average and Measures in a Date Matrix

Hi!

I'm trying to add on the line part the avarenge of the values of the row columns from a matrix and I don't know how to do it yet. I tryed to google it and went to stackoverflow but didn't see some solution for it.

The point is that I have on the lines every (Client Id,Lifetime and the month-year of the churn) and for the columns I do have a (year-month) in sequence, for which year-month I got how many days in the month the client opened the software. I trying to add another line that's shows for each row the avarege of the values on it.

Can someone help me with that? :)!