Just did a quick google search, the article was written in 2014 so the annual GDP of Iceland leading up to that period were:
$13.3B in 2010
$14.7B in 2011
$14.3B in 2012
$15.6B in 2013
$17.3B in 2014
So presuming the article was written prior to the 2013 GDP figures being released then the statement was indeed correct when made (and may still be barring new information about revenue growth).