Above average - I have been to 8 of the places. Part of it is having been to NY several times and to London twice. And those would be where all the places are located. NY - Niagara Falls, Empire State Building, Times Square, and Statue of Liberty. England - Stonehenge, Big Ben, Buckingham Palace, and Tower Bridge.
Like someone else mentioned, I do think the list is a bit skewed as I really have not been out of the country other than Canada and Mexico (and of course England). The only other non-US location is Singapore, but I was a super young child and do not remember much about it.