Find out how complete a translation is based on the binary mo file

Based on the binary *.mo file I would like to find out how complete the language is translated. When I would have a *.po file it would be easy of course. I also tried de-compile the mo-file via unmsgfmt but this do not contain empty strings. Might it be possible to somehow count the empty strings while using msgfmt and store that info in an extra variable? Or is there any other approach?