Every country has a national holiday. Where do they all fall?

On the Fourth of July my daughter asked which other countries were celebrating their own version of it, and where all of those days sit on the calendar. Independence day turns out to be the wrong term for the question: France celebrates a revolution, China a founding, Denmark a constitution. So we used the CIA World Factbook, which names each country's one premier national day, whatever it commemorates. We plotted all 194 of them: the 193 UN members plus Taiwan and Kosovo, minus the United Kingdom, which has no single national day.