That’s an incredible chart. I’m not saying I don’t believe it, but it seems incredible. How can it possibly be true? What changed in the past 30 years?
In the first half of the last century, assets were valued with a gold standard. In the early 1970’s, the gold standard was removed. So, global wealth today is measured in inflated dollars, not gold. So, the chart really is not measuring oranges to oranges.
I am just guessing, here, but I suspect it is because the denominator (bottom) of the fraction - total world assets - expanded greatly over the past 90 years, while the numerator (top) of the fraction expanded only moderately.
The term "world assets" must include EVERYTHING - the total industrial base of all of the countries of the world, the military assets (aircraft carriers, etc.), the total number of automobiles and trucks, oil tankers, airplanes, dams, factories, canals, skyscrapers, all privately-owned cell phones, satellites, space shuttles, etc. - literally everything.
Consider the total value of the country of, e.g., Saudi Arabia in the year 1921 - and compare it with its value today. Take even a less obvious example, like Pakistan. In 1921, Pakistan wasn't even an independent nation, but let's pretend it was. How would you rate the military might (to name but a single aspect) of Pakistan in 1921 as compared with today? Modern-day Pakistan, if miraculously transported back in time to the year 1922, would undoubtedly be able to conquer the combined military might of all of the rest of the world's armies and navies.
In view of that, it's no wonder than a mere, e.g., 50-fold increase in the value of gold, and the paltry pentupling of the tonnage of extracted gold, should pale in comparison.
Regards,