Master_cylinder,
after thinking about this I suggest creating separates calculated measures (Excel 2010, in 2013 it's Calculated Fields) for each year that will allow easy filtering. It might be tricky if you have way to many years, but this way you can be sure the results are filtered exactly how you need to:
So for each year, create this simple measure:
=CALCULATE([Sum of Sales], Sales[Year]=2014)
For other years, simple change the filter parameter at the end - replace 2014 with different years. Than drag all the measures on the table, so that you will get something like this:
When you are done, simple filter the table using regular filter option and pick those settings:
This will get you the results you need.
PS: This is the powerpivot table structure that I was working with, and link to my source file in Excel (2010):