![](http://phibetaiota.net/wp-content/uploads/2012/12/arno-in-taiwan-150x150.png)
I will look into the 8 million a year possibilities. In the meanwhile, here are three links:
http://globalmissingkids.org/awareness/missing-children-statistics/
http://missingchildreneurope.eu/facts&figures
https://arkofhopeforchildren.org/child-trafficking/child-trafficking-statistics