I would love to see it plotted against other monarchs.
I've heard it said that the US Senate has had less turnover in recent decades (chance of a seat turning over in a given year) than the remaining monarchies of Europe, even including QE2 bringing up the average. I've often wondered whether or not that's true, but a cursory look found nothing. It could be one of those things that starts as rhetorical flourish and becomes fact through repeated use.