Forecasting based on rolling 4-year average

Thank you for your response. Unfortunately, neither the native visual nor a custom visual could really help as I need the actual data for further calculations.

I tried R but seeing that my company denies me admin rights on my own machine, that road went nowhere fast. In the end, I went back to good old PowerQuery and did it in M - coding the years based on the actuals to keep it generic for the future, then creating however many additional years I needed, pivoting the entire thing and converting the year-codes back to actual years. Easy but not really "pretty". 

Anyway, thank you both Anonymous and mahoneypat for trying to help. I really hope Power BI will get better native tools for statistics, forecasting and such in the future. Visualising data is not always enough. This scenario was actually very basic and it's a pitty that I could not find a smoother, more elegant solution.