I would creat dataitems one is for current year 2017 as case when date>=trunc(current_date,'YY') and date<=current_date then measure end
second is for prior year 2016 as case when date>=trunc(_add_years(current_date,-1),'YY') and date<=_add_years(curre...
second is for prior year 2016 as case when date>=trunc(_add_years(current_date,-1),'YY') and date<=_add_years(curre...