Rated 5 out of 5 stars

After not working for years due to a bug in Mozilla's source code, this add-on is now fully functional again.

The only thing I would like to be changed is to be able to exclude certain folders from the count.
Otherwise everything works just as expected.

Thanks a lot to the developer for maintaining this after so many years!

EDIT:
Sadly the addon seems to have stopped working again. Any chance that this will be fixed another time?
EDIT2:
The error seems to come from a recent code change.
see here: https://bugzilla.mozilla.org/show_bug.cgi?id=1457457#c23
EDIT3:
The bug has been fixed and the addon works again! (as of 2018-12-21)

This review is for a previous version of the add-on (1.2.20180408).