I have now uploaded the swine flu data to a Swivel data set. I will update this data set periodically and so the rankings in the chart below should stay reasonably up to date.
Data sources: Guardian Data Blog, CIA World Fact Book.
UPDATE: A number of people have told me that in a number of places, including Victoria and much of the US, testing for swine flu has ceased. This means that the “lab confirmed” swine flu count will become increasingly meaningless over time, so I have decided to stop updating this data.