Check for year tag if exist or not

I am using an action to move my music to my storage location, in the process I use the following action. Is there any way in an expression to check if the year field exists, if it does then append the '['%year%']' portion, if it is blank then leave it off . This works great until I have an album that I can't find the year then I end up with [] in the directory name.

Any thoughts,

thanks in advance

k:\Music Archive\Albums\%artist%\%album% '['%year%']'\%_filename%


k:\Music Archive\Albums\\%artist%\\%album%[ '['%year%']']\\%_filename%