Create a bar graph of average time per each, calculated with a measure

[Tobias6]

Hello,

I have a table with all the orders. Each order with 7 process steps. I've  calculated the time between the processes with a measure like picking time:

picking time = DATEDIFF(orderlist[printOrder], orderlist[packaging],DAY)

I like to show the average time of all proccess steps in a bar graph for selected or all orders choosen by a filter.
It's not possible to aggregate a measure like a coloumn to average, sum, etc

My questions are:
What to do to get the avarage process time? 
How to set up the diagram when I have only measures for each process steps x/y axis?

Many thanks and best regards,
Tobias