The first major study of modern slavery shows that all 162 countries surveyed showed some level of slavery present, though the gap between the least and the most is enormous. The study includes forced labor, debt bondage, human trafficking, and forced marriage. By this definition, slavery may account for 2 ? 4% of the labor market in some industries. India turned up as one of the worse perpetrators at number one by sheer quantity of slaves, and number four in terms of the proportion of slaves out of total population. The top ten countries with the greatest number of total slaves account for 76% of slaves worldwide.
See "Slavery still grips tens of millions worldwide, report says", Jessica Hartogs, CBS News, October 16, 2013