I think the poll is largely meaningless. If you polled Americans in 1800, 1850, 1900, 1950, 2000 or any year you'd care to choose the results would be the same. The question has no context so most people will default to "none of my business" unless they've heard of the place or been there. How else can you explain such little regard for New Zealand.

When there is context things are different.