Some fun stuff from Runrepeat.com:
The purpose of this study was to compare recreational runners. Therefore elite runners were omitted hence including them would bias the results dramatically.
In this analysis, we looked at the following marathons from 2009 to 2014: Chicago, Marine, Boston, London, Paris, Berlin, Frankfurt, Athens, Amsterdam, Budapest, Warszawa and Madrid. This gave us a total of 72 marathon races.
Iceland’s got the world’s fastest non-elite marathon runners. Men clock in at ~3:52, Women at 4:18. Pretty impressive. In comparison, men in the US finish at around 4:19, while women finish at ~4:42. Developed and rapidly developing countries seem to see the largest increase in marathon runnings between 2009-2014.