Which nation has been most affected by slavery in 20th century?

It is really hard to tell which country has been the
most affected, since the traffic is illegal, and largely invisible
to the public.  I would have to say that Mexico is one of those most affected though. 
There is a vast amount of drugs, legal goods and humans that cross the border from
Mexico into the United States every day, and along with that traffic is, tragically and
horribly, slave trafficking as well.

Most of the victims
are children and teenagers, and are sold into sexual slavery inside the United
States.

There are other countries where slave laborers are
still sold, including in and between some African countries.  Follow the links below to
the United Nations site on human trafficking and domestic
slavery.