My immediate thought when reading this was that the number of people is much higher today than 50 years ago, but before my kneejerk reaction I decided to check the math. Assuming the results of a quick google can be trusted, we have around 4 billion more people today than 50 years ago, which means that entire percent of the population growth in the past 50 years are people in slavery. That's staggeringly higher than I would have estimated before reading any of this.