Yes it’s deliberately worded to be vague it could really mean either with no source, I did some research and most of what I found was multiple books are being published by people, with that same 1/10 being repeated, didn’t look into publishing rates or anything yet though.
When I visited (so take it with a grain of salt) a local (who was a friend of a friend and showed us around) said that culturally there is a lot of encouragement to be creative in various forms. Be interested if any Icelandic people would either confirm or deny this.