Follow this if you want to know how well you are doing now compared to previous years.
Go to register reports
Now select the item marked "Sales Comparison for a Given period".
Note you can do it by a supplier, but that can be done later.
Now select the dates that you wish to compare. In this example, I have used 2015 and compared to a similar period last year.
I would recommend as a first attempt comparing
2/12/2016 to 22/12/2016 AND 1/12/2017 to 21/12/2017
Now out will appear pages of detailed information showing how you are performing now compared to the previous period.
After analysing this check out this year 2015 and compared it to now.
This should give you a pretty good idea of how you are travelling now.
This is just another example of how powerful our point of sale software is for retail management.