Not too surprising when you think about it; it correlates well with high incidence of seasonal affective disorder and general lack of sunlight, as caffeine is a natural antidepressant. Same reason it's so popular in Seattle.
Based on this data, geeks are most likely vikings.
I'd be curious to see these statistics mashed up with some productivity stats per capita.
Interesting. Yes, that could be a good part two.
As an Italian coffee addict that moved to the States.. I can only warn you that measuring "productivity" in Italy can be a 'daunting' task. That being said, I'd be one more reader interested in the topic.