Hi Jason Kleinhans,
Ideally, you would like a comparative dashboard with 2015 and 2016 (or other comparative dates).
The problem is that you are unable to merge all the months from a single year, with your calendar calculation, right?
It's not my preferred topic, but I will try to add my brain to this problem, so we can progress further together
Lénaïc RIÉDINGER, Global Community Engineer Tableau
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Not quite sure what it is the graph should show.
If it's a comparison between your current year results vs previous year(s) then you're making it quite complex (no offence). We have several reports where we compare the results YTD + the ability to use a parameter to adjust the months. See screenshot below.
In this screenshot we show the current (year) results until the month in a parameter.
The previous year(s) are shown below that point. In this case we also show (in blue) the rest of the previous years results so they have an idea of 'what's to come'. This is optional :-)
If this is what you're looking for, just let me know. I can provide a sample based on your data. All I need to know is the correct date-field.