Out of curiosity I had a short look at various map formats how much space they need for a certain country. I picked (for no certain reason) Bulgaria.
PS: Of course various maps may contain a various degree of details in the data which I did not check.
PPS: Fixed OSMAnd and mapsforge after Zverik’s hint (used a third party website before with obviously outdated data).
Comment from Zverik on 24 January 2016 at 20:24
Osmand = 68 MB: http://download.osmand.net/rawindexes/
Comment from malenki on 24 January 2016 at 21:15
Thank you for the hint – I knew I should have looked for primary sources. *sigh*
Though that OSMAnd page shows me 67,2MB.
I updated the posting accordingly.