SAP Bex Query Designer Year to date

Hi all

I am trying to build a report that shows 2018 vs 2017 year to date. Of course 2018 will show the 2018 YTD number, however I cannot get 2017 to show the YTD number. I don't want the user to select any year or month, when the query refreshes it should just pickup the correct dates.

I tried putting a structure in using Invoice Year and then selecting Current Year -1 but that does not work. Any Suggestions?

Thanks

James