Decomposed - I put TWO LINKS in my post - the WaPo link was a 'quickie' and insignificant in comparison to the FIRST LINK.
I did not mean to jump in to your conversation with Micro yet when anyone states that 40+Million people in SLAVERY "works out to about one half of one percent of the world's population... and that's well within the margin of error of most statistical samplings. In other words, the number could possibly be 2.5 percent or it could be zero. So, I question the number." all I can say is that marginalizing 40+ MILLION people is a grossly EDIT: misinformed thing to state - especially IF you are one of the 40,000,000++!!!
Here is the link again to the interactive map of Global Slavery I posted that you missed - very enlightening.
http://www.globalslaveryindex.org/2018/data/maps/#prevalence
This link is to the 2018 Global Slavery Index from the Walk Free Foundation - the file is almost 59MB and 276 pages and should eliminate ANY AND ALL doubt that slavery is rampant and was not eradicated as you seem to think it was 100+ years ago. It is a comprehensive file that you will enjoy.
http://www.globalslaveryindex.org/resources/downloads/
PEACE!!!