help custom column

Hi. First of all, I would like to thank everyone for the timely feedback that I am very helpful.

So, I've two aggregate columns which sum the import for each year (2016/2017). I would insert a custom column which the % difference (2017/2016) and I don't see the way. The custom column doesn't have sense in the query that has the list of detail. I would be good if I could have this column on which put the sort..... Help me, please...... Thank you...