Ah, you are the maker of the graphic. Well, I vaguely remember the graphic I saw. But as a feedback - What are the two extremes? I don't know the end points i

Ah, you are the maker of the graphic. Well, I vaguely remember the graphic I saw. But as a feedback - What are the two extremes? I don't know the end points in your graphic. - You graphic does not show how the center shifted from the East to the west after the industrial revolution. Because from 1500 to 2010 you actually have either hard data or past estimates. - I would have put the distance of the dots (years) and a color legend in the picture. - I am to stupid to understand what the different sized arrows mean in the graphic. What information do they provide?