You can see prior years but not if it is real time calculations from the omitted records. By the nature omitted records are not included. I would suggest prior year data be real numbers that are not calculated once moving to a prior year status.
I duplicated the object under relationships, made the relationship from the main database of the year -1 to the secondary database of year. So it always adds the data from previous year(s) to current record. This works so good I had to post it...
So, when in 2015, I also see the previous years data.
ExecuteSQL could also produce such a total.