Basic date handling in DAX

One of the things that you learn very quickly in the tabular model is that you always need to have a date table. I thought that for my Hans Rosling project I could get away without one, since the data is captured only annually. Surely you should be able to do year-over-year calculations and get the previous year in DAX from the row context, right? Wrong. After much trial and error (read: error), I made the date table and got the calculations to work.