There is substantial disagreement about New World population levels. Maddison seems to have written before 1491 publicized evidence that smallpox killed most people there before Europeans made much contact with them. I used the estimate of 100 million that I got from 1491′s Wikipedia page, but that’s likely near the high end of expert guesses.
I don’t know about population sizes either. Maddison (cited at https://en.wikipedia.org/wiki/Estimates_of_historical_world_population#By_world_region) says that in 1500, Americans were only about 4% of global population, with 20% being in Europe and 68% in Asia.
There is substantial disagreement about New World population levels. Maddison seems to have written before 1491 publicized evidence that smallpox killed most people there before Europeans made much contact with them. I used the estimate of 100 million that I got from 1491′s Wikipedia page, but that’s likely near the high end of expert guesses.