Potatoes and the Irish
We have probably all heard the stories about the Irish and the famine following the failure in potato crops in the 19th century. This chart really brings the point home.
The Irish population peaked in 1845 at just over 6 million people, then fell to below 3 million in the mid 1900s, reaching a low point in 1961. Now the population is just over 4 million, but was not even expected to have reached the previous heights by 2030 when this projection was made a couple of years ago.
It remains to be seen how the current developments in the Irish economy will affect these numbers.
P.S. This entry demonstrates some of the features of DataMarket's marvelous embed mechanism. Anybody can make such a graph and use on their own blogs or news sites. Simply find the data set, select the time series for your story, create any markers you might want to show and then click the "Embed on website" button to retrieve your code.