"A survey found people from each country think it was responsible for contributing more than half to the victory - the UK (51%), the US (54%) and Russia (75%)."
For myself, I think this is poorly worded and deliberately divisive. Why remember history as a competition for spoils?
The British and its allies, including heroic countries like Canada and Australia, averted a quick loss of the war.
The Russians, having started on the other side, turned the tide.
The Americans, joining late, provided the force that helped end the war.
Each contributed. None could have won without the contribution of the others. Why make it a competition when it was a cooperative engagement in which one might more generously remember the help of others in pursuing a just cause?
http://www.dailymail.co.uk/sciencetech/article-7349297/National-narcissism-means-Britons-Americans-Russians-think-won-WWII.html