A couple of years ago reddit user depo_ made a map of heavy metal bands per capita. Following his/her lead, I made these map and chart with punk and hardcore bands per capita, but only with bands from the 1970s and 1980s. The data for the bands comes from Kill From The Heart and the population data (based on 1980) from Wikipedia.
It seems that besides volcanoes and glaciers Iceland had also many punk bands in the 1980s. This explains the mayor of Reykjavík getting a Crass tattoo.