According to the QI (Quite Interesting) team, independence from Britain is celebrated somewhere in the world, on average, once every seven days. More countries were colonized by Britain than any other country in the world. Of all the nations in the world, 65 of those countries secured their independence from the United Kingdom or some form of British military occupation, and 48 of those have a national day of celebration.
That works out to approximately one celebration ever 7 days. It is believed to be the most celebrated national holiday (outside of religious holidays) than any other. Pretty cool for both sides, in my opinion. Just think of how massive the British Empire once was.