Roll-Up Field for YTD Sales in the Product Entity

Hi all,

I'm trying to display the YTD and LYTD Sales for each item in Microsoft CRM 365. Right now I have it set up as a Roll-Up field:

This summarizes the sales of the item, and works well.

The thing is that this roll-up field will not start over when we reach 2017. Someone has to manually change the roll-up field each year, which I want to avoid.

Does anyone have an idea of how to set up the field to only calculate for 2016, and then start over in january for the sales in 2017? 

If possible I would also want to display the total sales for 2012, 2013, 2014 and 2015 - and I want these fields to be dynamic. So when we reach 2017, I want the total sales for 2013, 2014, 2015 and 2016 to show. 

Any ideas?

Thanks