Apart from the jab to WWII, which honestly made no sense whatsoever because as soon as Mussolini (which let me remind you was a DICTATOR, so the population didn't choose to side with Germany in the war or to go to war AT ALL) was sent to jail, Partisans immediately intensified their work and started freeing the North of the country before the Anglo-Americans and the new Italian government could even strike up a deal.
Also, I'm not really too sure you should be so proud of your intervention in the South of Italy, since there are some pretty strong rumours about you allying yourselves with the Sicilian mafia during those years. Just saying.
Back on track, all of the poorer countries have received more benefits than costs after joining the EU. The exception is Greece, but I fail to see how that example could be relevant since they falsified their economic data to join the EU. Had they had the requisites to enter they probably wouldn't have suffered the crisis as much as they did.
If you want to have a source on per capita GDP after and before countries joining the EU, I'd recommend you read this article by VOX, which I happen to think is a pretty unbiased source:
http://voxeu.org/article/how-poorer-nations-benefit-eu-membership However, in case you were too lazy, let me just post the graph of some of the "poorer countries".