Year filter is not ignored in the main(outer) set expression, hence it shows only the selected year data. What are you actually trying to achieve? P() should be used if you wish to get all sales for the customers who have participated in 2014,2013. And mind it, if a customer A is there in sale either in 2015 or 2014 ... all it's sales even beyond 2014 would come up with p(). Do you want that?