Not sure whether they specify this number in their quarterly reports, but given that it's "the world" vs the US revenue it is definitely a majority.
Edit: 17 billion out of 40 billion (both in euros and 2013 figures) global revenue runs through Google Ireland Ltd alone and that's reported as ad sales from Europe only. I did not find a report for the Netherlands, but there is more revenue from outside Europe taking this route as well since it's the cheapest route for anything that is not coming from the US.
For the latest quarter: "Our revenues from outside of the United States totaled $9.55 billion, representing 58% of total revenues in the third quarter of 2014, compared to 58% in the second quarter of 2014 and 56% in the third quarter of 2013."
Unless the rest of the world outside of Europe only has ~8%, and or all global revenue actually does go through Ireland & Co (again, I'm skeptical it's 100%). That's possible, but it's seems unlikely.
From the Wikipedia page: "The offshore company continues to receive all of the profits from exploitation of the rights outside the US, but without paying US tax on the profits unless and until they are remitted to the US.[5]"
So yes: all of it goes through Europe.
