Dropbox inquiry

Good evening. I am working on a 52 week file where various sales are entered from different departments on a daily/weekly basis. What I am trying to do is combine annually also. Currently I have a main page that shows a running total for each department annually or I can select the specific week, however I am also trying to create a dropbox to select a specific year also to view that information necessary however I do not know how to make a drop box to view information from a closed book. Alternatively I am curious if it is possible to display a previous year (book)'s data in 1 opened workbook. Essentially if I was viewing 2016 sales to see 2015's sales in a +/- ratio. Any and all help would be appreciated. Thanks.

You can create a sync folder for Dropbox on your local machine and use it just like any other folder for opening workbooks. You could even use formulas to pull the data from the workbooks without any VBA