Data from the CIA World Factbook provides a calculation of the age distribution of every country on earth. The figures are loosely grouped, so the most accurate figure we can get for many countries is the size of the population aged 65 or over. In other words, we have a tally of the number of people who were born in the mid-1950s (depending on the recency of the CIA estimates) — so approximately the number of people who were alive before Elizabeth’s ascension.
The dark purple below indicates the fraction of each country’s population that is 65 or over — and possibly was born before Elizabeth’s reign.
You can see both how much of each country’s population was born after Elizabeth assumed the throne — and how the age of national populations varies around the world. In Europe and North America, there is a much higher density of older people than in Africa, for example.
According to the World Factbook’s data, about 10 percent of the global population is aged 65 and over. In Britain, though, that figure is nearly 19 percent, and just over the 17 percent in the United States. Near the poles are Japan and Nigeria — the former with a much more heavily old population, and the latter with a much less heavily old one.
We can view this a bit differently. The graph below shows the entirety of the measured world population. The boxes in dark purple are the segments of each country’s population age 65 or older. The light-colored boxes are the population born after Elizabeth became queen. That includes more than 53 million British residents (shown near the bottom right), just to give a sense of scale.
That’s an estimate, of course, since “over 65” is not equivalent to “born before 1952.” In the United States, though, Census Bureau data gives us a more precise sense of the population that’s never experienced a non-Queen Elizabeth II world.
About 8 in 9 U.S. residents were born in or after 1952.
Notice the gap between that 11.2 percent figure and the 16.9 percent in the World Factbook data. That’s because about 18 million Americans are 65 or older but born after 1951. Our numbers are skewed somewhat since Elizabeth took the throne in the middle of a massive population surge here (the baby boom). But it reflects how other countries might similarly have fewer pre-Elizabeth residents than the figures above suggest.
Precision isn’t really the point here. Instead, it’s scale. The vast majority of the living human population has always existed alongside her royal highness Queen Elizabeth II.