I tried with * but that only extracts 1 file, and in a second test Qlikview crashed.
Quick work around is to repeat the load in a second load script and concatenate the files, or store them in separate QVD's.
If your history doesn't change then there will be no need to reload all files each time. Keep your history in separate QVD's and only load the active period. Then you will only have to change the source file in your script each year.
Add 'Filename() as Source' (for instance) to identify the source file.