Please see the attached twbx. I have created two calculations which give the previous YTD and current YTD value. I base this on today's date, so YTD would be 2018 year up until June.
To get the years in the same chart, you'd have to create 4 more fields, one which is for full current year sales value, then one for last year's sales value etc. In my example I have already created the current year and previous year values (first two bars).
try1_v10.2.twbx 1.2 MB