You need to select cell K4, then click on Data | Data Validation | Data Validation (yes, twice), and then you will see the list of years separated by a comma. Add other years to the end of the list, with a comma between them, and you can remove earlier years from the list if you no longer need them - Data Validation drop-downs only show 8 items on screen, so by removing the earlier years you won't have to scroll down so much.

It would help to understand your 2-table query if you attached a sample Excel workbook. To do this, click on Go Advanced (below the Edit Window) while you are composing a reply, then scroll down to and click on Manage Attachments and the Upload window will open. Click on Browse and navigate to (and double-click) the file icon that you want to attach, then click on Upload and Close this Window to return to the Edit window. When you have finished composing your post, click on Submit Post.

Pete